Patent Description:
The present disclosure generally relates to manufacture of high density interconnects for densely packed or segmented light emitting diodes or lasers. Transparent conductive oxides may provide some of the interconnects.

<CIT> discloses monolithic LED chips having a plurality of active areas on a substrate/submount ("submount") that can be interconnected in series. The active areas can be arranged in close proximity such that space between adjacent ones of the active areas is substantially not visible when the emitter is emitting, thereby allowing the LED chip to emit light similar to that of a filament.

<CIT> discloses a light engine array comprises a multiple light engines arranged into an array, multiple dams located on a first surface of the light engines; and the dams combined a dam array.

<CIT> discloses a light emitting diode, comprising: a transparent substrate; a wiring layer; and a semiconductor light emitting element structure part between the transparent substrate and the wiring layer, the semiconductor light emitting element structure part further comprising: a semiconductor light emitting layer; a transparent conductive layer provided on the wiring layer side of the semiconductor light emitting layer; a transparent insulating film; a metal reflection layer; and a first electrode part and a second electrode part provided on the wiring layer side of the transparent insulating film, to be electrically connected to the wiring layer, wherein the first electrode part is electrically connected to the first semiconductor layer via a first contact part which is provided to pass through the transparent insulating film, and the second electrode part is electrically connected to the second semiconductor layer by a second contact part provided to pass through the transparent insulating film, the transparent conductive layer, the first semiconductor layer, and the active layer.

A light emitting diode (LED) includes a conductive via in a first portion of an epitaxial layer and a p-type contact on a second portion of the epitaxial layer. The first portion and the second portion are separated by an isolation region. The LED includes a transparent conductive layer on the epitaxial layer.

Examples of different light illumination systems and/or light emitting diode implementations will be described more fully hereinafter with reference to the accompanying drawings. These examples are not mutually exclusive, and features found in one example may be combined with features found in one or more other examples to achieve additional implementations. Accordingly, it will be understood that the examples shown in the accompanying drawings are provided for illustrative purposes only and they are not intended to limit the disclosure in any way.

It will be understood that, although the terms first, second, third, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms may be used to distinguish one element from another. For example, a first element may be termed a second element and a second element may be termed a first element without departing from the scope of the present invention. As used herein, the term "and/or" may include any and all combinations of one or more of the associated listed items.

It will be understood that when an element such as a layer, region, or substrate is referred to as being "on" or extending "onto" another element, it may be directly on or extend directly onto the other element or intervening elements may also be present. In contrast, when an element is referred to as being "directly on" or extending "directly onto" another element, there may be no intervening elements present. It will also be understood that when an element is referred to as being "connected" or "coupled" to another element, it may be directly connected or coupled to the other element and/or connected or coupled to the other element via one or more intervening elements. In contrast, when an element is referred to as being "directly connected" or "directly coupled" to another element, there are no intervening elements present between the element and the other element. It will be understood that these terms are intended to encompass different orientations of the element in addition to any orientation depicted in the figures.

Relative terms such as "below," "above," "upper,", "lower," "horizontal" or "vertical" may be used herein to describe a relationship of one element, layer, or region to another element, layer, or region as illustrated in the figures. It will be understood that these terms are intended to encompass different orientations of the device in addition to the orientation depicted in the figures.

Semiconductor light emitting devices or optical power emitting devices, such as devices that emit ultraviolet (UV) or infrared (IR) optical power, are among the most efficient light sources currently available. These devices may include light emitting diodes, resonant cavity light emitting diodes, vertical cavity laser diodes, edge emitting lasers, or the like (hereinafter referred to as "LEDs"). Due to their compact size and lower power requirements, for example, LEDs may be attractive candidates for many different applications. For example, they may be used as light sources (e.g., flash lights and camera flashes) for hand-held battery-powered devices, such as cameras and cell phones. They may also be used, for example, for automotive lighting, heads up display (HUD) lighting, horticultural lighting, street lighting, torch for video, general illumination (e.g., home, shop, office and studio lighting, theater/stage lighting and architectural lighting), augmented reality (AR) lighting, virtual reality (VR) lighting, as back lights for displays, and IR spectroscopy. A single LED may provide light that is less bright than an incandescent light source, and, therefore, multi-junction devices or arrays of LEDs (such as monolithic LED arrays, micro LED arrays, etc.) may be used for applications where more brightness is desired or required.

Semiconductor light-emitting devices can be arranged or formed in densely packed groups or blocks. However, when a light-emitting device is small, or many light-emitting devices are grouped together, providing reliable interconnections is difficult, particularly if each light-emitting device must be separately addressable.

In accordance with embodiments of the invention, a segmented LED interconnect system includes a plurality of LED segments, each segment having a p-layer positioned on a n-layer. An optically transparent conductive line is attached to multiple n-layers of multiple LED segments, and a conductive line is attached to multiple p-layers of multiple LED segments. A wire bond can be connected to the optically transparent conductive line. In various embodiments, each LED segment can be addressably connected using a crossbar or other suitable electrical connection scheme that allows selective light emission from single or multiple LED segments in definable patterns.

In another embodiment, a method of manufacturing a segmented LED interconnect system includes the steps of sequentially growing an n-layer and a p-layer on a substrate. Channels are etched through the p-layer and the n-layer to the substrate to define multiple LED segments. Electrical contacts are defined on the p-layer are attached to a PCB substrate, which may be a LED device attach region <NUM> as described below, followed by removal of the substrate. Optically transparent conductive lines connected to multiple n-layers of multiple LED segments, and the optically transparent conductive lines are connected to the PCB substrate.

As seen in <FIG>, a segmented LED interconnect system <NUM> includes a plurality of LED segments <NUM> (i. e, a light emitting pixel array) separated from each other by a dielectric material <NUM>. Each LED segment <NUM> has a p-layer <NUM> positioned on a n-layer <NUM> to together define an active region capable of emitting light in response to an applied electrical current. To provide needed electrical connections, optically transparent conductive lines <NUM> are attached to the multiple n-layers <NUM> of multiple LED segments <NUM>, with the optically transparent conductive lines <NUM> extending across multiple LED segments and on top of the dielectric material <NUM>. A conductive line <NUM> formed on a printed circuit board (PCB) substrate <NUM> is attached to a conductive pad <NUM> formed on each p-layer <NUM>, providing an electrical connection to multiple p-layers <NUM> of the multiple LED segments <NUM>. A wire bond <NUM> is connected to the optically transparent conductive line <NUM> to allow formation of an electrical circuit passing through the p-layer <NUM> and n-layer <NUM>.

Each of the plurality of LED segments can be sized to laterally extend between <NUM> and <NUM> microns, or more typically, between <NUM> and <NUM> microns, with channels separating the segments being filled with an optically and electrically isolating dielectric material <NUM>. LED segments can have a square, rectangular, polygonal, circular, arcuate or other surface shape. Channels can be of uniform width and length, or can vary as needed. Pixel arrays of the LED segments can be arranged in geometrically straight rows and columns, staggered rows or columns, curving lines, or semi-random or random layouts. Single or multiple lines of LED segments are also supported. In some embodiments, radial or other non-rectangular grid arrangements of conductive lines to the LED segments can be used. In other embodiments, curving, winding, serpentine, and/or other suitable non-linear arrangements of conductive lines to the LED segments can be used.

<FIG> illustrate process steps for manufacture of an embodiment. As seen with respect to <FIG>, a substrate <NUM>, typically formed of sapphire or silicon carbide, supports an epitaxially grown or deposited semiconductor n-layer <NUM>. A semiconductor p-layer <NUM> is sequentially grown or deposited on the n-layer <NUM>, forming an active region at the junction between layers. Semiconductor materials capable of forming high-brightness light emitting devices can include, but are not limited to, Group III-V semiconductors, particularly binary, ternary, and quaternary alloys of gallium, aluminum, indium, and nitrogen, also referred to as III-nitride materials. Such semiconductor materials can be grown to support both LED and laser systems as necessary.

<FIG> illustrates deposition of a metallic conductive layer <NUM> in contact with the p-layer <NUM>. The metal can be deposited by evaporation or other suitable deposition process, and can include an aluminum/gold bilayer, silver, or other solderable and conductive material. As seen in <FIG>, selective masking and etching, or alternatively, direct patterned etching, can be used to define electrical contacts <NUM> on the p-layer. As seen in <FIG>, a second round of selective masking and etching, or alternatively, direct patterned etching, can be used to define channels <NUM> through both the p-layer <NUM> and n-layer <NUM> to the substrate <NUM>. The remaining material between the etched channels in turn defines LED segments <NUM>. In <FIG>, sidewalls <NUM> of the channels <NUM> are optionally coated with light absorbers, reflectors (including stack of dielectric layers that form a distributed Bragg reflector), other optical coating, or electrically insulative material. The channel <NUM> is then filled with an optically and electrically isolating dielectric material <NUM> that can include organic, inorganic, or organic/inorganic binder and filler material. For example, acrylate or nitrocellulose can be used in conjunction with ceramic particles. Another organic/inorganic binder and filler can be, for example, epoxy with embedded reflective titanium oxide or other reflective/scattering particles. Inorganic binders can include sol-gel (e.g., a sol-gel of TEOS or MTMS) or liquid glass (e.g., sodium silicate or potassium silicate), also known as water glass. In some embodiments binders can include fillers that adjust physical properties. Fillers can include inorganic nanoparticles, silica, glass particles or fibers, or other materials able to improve optical or thermal performance.

In <FIG>, the structure is inverted and attached (after heating and reflow) using electrical contacts <NUM> to a printed circuit board (PCB) substrate <NUM>. The PCB substrate supports conductive lines <NUM> that extend between each LED segment and suitable electric power and drive circuitry (not shown) that is also positionable on the PCB substrate <NUM>.

In <FIG>, laser liftoff or other epitaxial film separation processes is applied to remove the sapphire substrate <NUM> (not shown). Polishing or photo electrochemical etching could be applied to modify surface and optical properties of the n-layer <NUM> for each LED segment. When the surface of n-layer <NUM> is readied, transparent conductive lines <NUM> of a transparent conductor such as antimony tin oxide (ATO), indium tin oxide (ITO), silver nanowires, or doped conductive graphene are deposited. Each grouping of transparent conductor can be deposited in separate, distinct lines, strings, pads, or blocks. Complex curved, circular, or winding layouts are possible. In the next step seen in <FIG>, a wirebond <NUM> is used to attach at least some of the transparent conductive lines <NUM> to the PCB substrate <NUM>. In other embodiments, a separate PCB substrate (not shown) can be connected to, as well as other suitable interposers or electrically conductive boards.

As will be appreciated, various additions other modifications to the above-described LED architecture and process are possible. LED segments can be overlain with wavelength converting materials such as phosphors, quantum dots, or dyes. Multiple types and thicknesses of phosphors can be used. An LED combined with one or more wavelength converting materials may be used to create white light or monochromatic light of other colors. All or only a portion of the light emitted by the LED segment may be converted by the wavelength converting material. Unconverted light may be part of the final spectrum of light, though it need not be. Examples of common devices include a blue-emitting LED segment combined with a yellow-emitting phosphor, a blue-emitting LED segment combined with green- and red-emitting phosphors, a UV-emitting LED segment combined with blue- and yellow-emitting phosphors, and a UV-emitting LED segment combined with blue-, green-, and red-emitting phosphors. The phosphors can be electrophoretically deposited on an LED segment with application of a voltage to a particular transparent conductor string. Varying applied voltage duration will correspondingly vary amount and thickness of deposited phosphors. Alternatively, the LED segment can be coated with the phosphor, using an organic binder to adhere the phosphor particles to the LED. Phosphors can be dispensed, screen printed, sprayed, molded, or laminated. Alternatively, for certain applications, a phosphor contained in glass, or a pre-formed sintered ceramic phosphor can be attached to the LED.

In some embodiments, microlenses or other primary or secondary optical elements (including reflectors, scattering elements, or absorbers) may be attached to each LED segment or associated phosphor. In other embodiments, a primary optic can be positioned over the entire array of LED segments, and directly attached or mounted at a distance from the LED segments in suitable packaging. Protective layers, transparent layers, thermal layers, or other packaging structures can be used as needed for specific applications.

<FIG> illustrate an alternative process and structure embodiment that shares processing details discussed with respect to <FIG>. However, during the etch step to define channels, in the embodiment of <FIG>, a blind via <NUM> extending through the p-layer <NUM> and into the n-layer <NUM> is etched, stopping before reaching the substrate <NUM>. Sidewalls of the via can be coated with silicon dioxide or other suitable electrical insulator <NUM>, with the bottom of the channel remaining exposed. The blind via is filled with an electrically conductive metal that provides contact between the exposed n-layer <NUM> and previously formed conductive pad <NUM>. As seen with respect to <FIG>, this allows the structure to be inverted and attached to PCB substrate <NUM> using supported conductive lines <NUM> and n-contact conductive pad <NUM>. Also attached are p-contact conductive pad <NUM>, allowing addressable electrical activation of the LED segment. Advantageously, use of the blind via <NUM> allows for complete or partial retention of the sapphire substrate, since wirebond connections to the top of the n-layer <NUM> are not necessary.

<FIG> illustrates one layout embodiment 1300A for top and bottom conductive lines extending to LED segments arranged in a pixel array. Conductive lines 1322A can be laid out as columns, with each LED segment 1301A being connected. Transparent conductive lines 1316A can be laid out to extend over rows of LEDs segments, with a connection to a PCB substrate made with wire bonds 1330A or other suitable electrical contact or trace. Together, conductive lines 1322A and 1316A form a crossbar allowing activation (addressing) of selected pixels, lines of pixels, or blocks of pixels.

<FIG> illustrates another layout embodiment 1300B for top and bottom conductive lines extending to LED segments arranged in a pixel array. Conductive lines 1322B can be laid out as columns, with each LED segment 1301B being connected. Transparent conductive lines 1316B can be laid out to extend over at least a portion of a row of LEDs segments, with a connection to a PCB substrate made with wire bonds 1330B or other suitable electrical contact or trace. Row conductive lines 1343B can be connected to buried via n-contacts 1334B. Advantageously, this allows n-contacts of LED segments positioned on an edge of the pixel array to be connected via wirebonds, while the internally situated LED segments that would be difficult to wirebond can be connected by the buried n-contacts 1334B.

<FIG> illustrates another layout embodiment 1300C for top and bottom conductive lines extending to LED segments having alternating white (W) and colored (C) phosphors arranged in a pixel array. Each pair of white and colored LED segment can be interconnected so that both are simultaneously activatable to emit light. Conductive lines 1322C can be laid out as columns, with each LED segment 1301C being connected. Transparent conductive lines 1316C can be laid out to extend over at least a portion of a row of LEDs segments, with a connection to a PCB substrate made with wire bonds 1330C or other suitable electrical contact or trace. Advantageously, in some embodiments this allows operation using AC current.

Referring now to <FIG>, a perspective view of a segmented LED <NUM> is shown. The segmented LED emitter <NUM> may include a first pixel 1707a, a second pixel 1707b, a third pixel 1707c, and a fourth pixel 1707d (i.e., "LED segments"). The first pixel 1707a may be separated from the second pixel 1707b by a first dielectric filled channel <NUM>. The third pixel 1707c and the fourth pixel 1707d may be separated by the first dielectric channel <NUM>.

The pixels may have a p-type layer <NUM> positioned on a n-type layer <NUM> to together define an active region capable of emitting light in response to an applied electrical current. The first dielectric filled channel <NUM> may extend through the entire n-type layer <NUM> and the entire p-type layer <NUM> in the x direction to electrically isolate the first pixel 1707a and the second pixel 1707b in that direction. In the y direction, a second dielectric filled channel <NUM> may extend through the entire p-type layer <NUM>, but only through a portion of the height of the n-type layer <NUM>. This may allow electrically conductivity in the y direction.

A first conductive line <NUM> formed on a printed circuit board (PCB) substrate <NUM> may be attached to a conductive pad <NUM> formed, providing an electrical connection to the first pixel 1707a and the second pixel 1707b. The first conductive line <NUM> may be an n-type contact. As described in more detail below, the conductive pad <NUM> may be formed on an insulated conductive via <NUM> that may carry the electrical connection to the n-type layer <NUM>. Because the second dielectric filled channel <NUM> does not extend through the entire thickness of the n-type layer <NUM>, the electrical connection from the first conductive line <NUM> may extend through the n-type layer <NUM> in the x direction. A second conductive line <NUM> formed on the PCB substrate <NUM> may be attached to a conductive pad <NUM> formed on the p-type layer <NUM>. Because the second dielectric filled channel <NUM> extends through the entire thickness of the p-type layer <NUM>, a second conductive line <NUM> may be placed on either side of the second dielectric filled channel <NUM>. The second dielectric filled channel <NUM> may define multiple emitters associated with each second conductive line <NUM>.

The LED segments may be sized to laterally extend between <NUM> and <NUM> microns, or more typically, between <NUM> and <NUM> microns. The first dielectric filled channel <NUM> and the second dielectric filled channel <NUM> separating the segments may be filled with an optically and electrically isolating dielectric material. The LED segments may have a square, rectangular, polygonal, circular, arcuate or other surface shape. The first dielectric filled channel <NUM> and the second dielectric filled channel <NUM> may be of uniform width and length, or may vary as needed. Pixel arrays of the LED segments can be arranged in geometrically straight rows and columns, staggered rows or columns, curving lines, or semi-random or random layouts. Single or multiple lines of LED segments are also supported. Radial or other non-rectangular grid arrangements of conductive lines to the LED segments may be used. Curving, winding, serpentine, and/or other suitable non-linear arrangements of conductive lines to the LED segments may be used.

Referring to <FIG> cross section views illustrating process steps for forming the segmented LED emitter <NUM> are shown. <FIG> illustrate the segmented LED interconnect system from the x direction. As seen with respect to <FIG>, a substrate <NUM>, typically formed of sapphire or silicon carbide, may support an epitaxially grown or deposited semiconductor n-type layer <NUM>. A semiconductor p-type layer <NUM> is sequentially grown or deposited on the n-type layer <NUM>, forming an active region <NUM> at the junction between layers. The n-type layer <NUM>, the active region <NUM>, and the p-type layer <NUM> may be collectively referred to as an epitaxial layer <NUM>. Semiconductor materials capable of forming high-brightness light emitting devices can include, but are not limited to, Group III-V semiconductors, particularly binary, ternary, and quaternary alloys of gallium, aluminum, indium, and nitrogen, also referred to as III-nitride materials. Such semiconductor materials can be grown to support both LED and laser systems as necessary.

As seen in <FIG>, a conductive layer <NUM> may be formed on the p-type layer <NUM>. The conductive layer <NUM> may be may be composed of an electrically conductive material, such as a metal. The conductive layer <NUM> may be formed of any material that reflects visible light, such as, for example, a refractive metal. The conductive layer <NUM> may be composed of one or more of a metal such as silver, gold, copper, a metal stack, or combinations thereof. The conductive layer <NUM> may be formed by any method suitable for metal deposition, such as plating, atomic layer deposition (ALD), evaporation, reactive sputtering, chemical solution deposition, spin-on deposition, or other like processes.

As seen in <FIG>, metal contacts, including an n-type contact <NUM> and a p-type contact <NUM>, may be formed from the conductive layer <NUM> using selective masking and etching, or alternatively, direct patterned etching.

As seen in <FIG>, a second round of selective masking and etching, or alternatively, direct patterned etching, may be used to define a first channels <NUM> and a second channel <NUM>. The first channel <NUM> and the second channel <NUM> may extend through an entire thickness of the p-type layer <NUM> and a portion of the n-type layer <NUM>.

As seen in <FIG>, sidewalls of the first channel <NUM> may be coated with an insulating lining <NUM>, such as, silicon dioxide or another dielectric material. The insulating lining <NUM> may extend to an upper surface of the p-type layer <NUM>. The electrical insulator may be formed such that a portion of the n-type layer <NUM> at the bottom of the first channel <NUM> remains exposed. This may be done using a directional etching process.

As seen in <FIG>, a conductive via <NUM> may be formed in the first channel <NUM>. An isolation region <NUM> may be formed in the second channel <NUM>. The conductive via <NUM> may provide contact between the exposed n-type layer <NUM> and the n-type contact <NUM>. The conductive via <NUM> may be composed of an electrically conductive material, such as a metal. The conductive via <NUM> may be composed of one or more of a metal such as silver, gold, copper, a metal stack, or combinations thereof. The conductive via <NUM> may be formed by any method suitable for metal deposition, such as plating, ALD, evaporation, reactive sputtering, chemical solution deposition, spin-on deposition, or other like processes.

The insulator <NUM> may be an optically and/ electrically isolating dielectric material, that may include organic, inorganic, or organic/inorganic binder and filler material. For example, acrylate or nitrocellulose may be used in conjunction with ceramic particles. Another organic/inorganic binder and filler may be, for example, epoxy with embedded reflective titanium oxide or other reflective/scattering particles. Inorganic binders may include sol-gel (e.g., a sol-gel of TEOS or MTMS) or liquid glass (e.g., sodium silicate or potassium silicate), also known as water glass. Binders may include fillers that adjust physical properties. Fillers may include inorganic nanoparticles, silica, glass particles or fibers, or other materials able to improve optical or thermal performance.

Although not shown in <FIG>, sidewalls and a bottom of the second channel <NUM> may be coated with light absorbers, reflectors (including a stack of dielectric layers that form a distributed Bragg reflector), other optical coating, or electrically insulating material prior to the deposition of the insulator <NUM>. The insulator <NUM> may be formed using a conventional deposition technique, such as, for example, chemical vapor deposition (CVD), plasma enhanced chemical vapor deposition (PECVD), metal-organic chemical vapor deposition (MOCVD), ALD, evaporation, reactive sputtering, chemical solution deposition, spin-on deposition, or other like processes.

As seen in <FIG>, the structure may be inverted and attached (e.g., after heating and reflow) using the n-type contact <NUM> and p-type contacts <NUM> to a printed circuit board (PCB) substrate <NUM>. The PCB substrate <NUM> may support an n-type conductive line <NUM> and one or more p-type conductive lines <NUM> that extend between each segmented LED <NUM> and suitable electric power and drive circuitry (not shown) that may be positionable on the PCB substrate <NUM>.

Portions of the LED array <NUM> that are not occupied by pixels may be referred to as a non-emission portion <NUM> or "dead space. " The dimensions of the pixels <NUM> and the dimensions of the non-emission portion <NUM> may vary in the embodiments described herein. In an example, the non-emission portion may be a portion of the LED array <NUM> between an inner edge <NUM> of the conductive via <NUM> and an outer edge <NUM> of the LED array <NUM>. In another example, as shown in <FIG>, the non-emission portion <NUM> may be a portion of the LED array <NUM> between an outer edge <NUM> of the isolation region <NUM> and the outer edge <NUM> of the LED array <NUM>. The pixels <NUM> may have a width of approximately <NUM> to several millimeters. The non-emission portion <NUM> may have a width compared to the pixels <NUM>, such that it occupies approximately <NUM>% to approximately <NUM>% of the total width of the LED array <NUM>.

As described above, the insulating material may not extend through the entire thickness of the n-type layer <NUM>, which may provide conductivity in the n-type layer <NUM> between the second pixel 1707b and the fourth pixel 1707d. Current may flow through the n-type conductive line <NUM>, to the n-type contact <NUM>, to the conductive via <NUM>, to the n-type layer <NUM>. The current may be insulated from the p-type layer <NUM> by the insulating lining <NUM>. The flow of current through the n-type layer and the segmentation of the p-type layer by the insulator <NUM> may provide for different emitting sections (i.e., the second pixel 1707b and the fourth pixel 1707d).

It should be noted that the segmented LED emitter <NUM> may be formed with any number of pixels. For example, the segmented LED emitter <NUM> may only have one p-type contact <NUM>, resulting in only one pixel <NUM>. Examples of a single emitter segmented LED <NUM> are described herein. The p-type contact <NUM> may be between the insulator <NUM> and the conductive via <NUM> to form the first pixel 1707a. In <FIG>, the insulator <NUM> may be located between the p-type contact <NUM> and the conductive via <NUM> to form a single pixel <NUM>. In <FIG>, the insulator <NUM> may not be formed, resulting in a larger pixel <NUM>.

<FIG> shows an optional underfill layer <NUM> between the epitaxial layer <NUM> and the PCB <NUM>. The underfill layer <NUM> may be composed of a conventional electrically and/or thermally insulating material, such as a dielectric. The underfill layer <NUM> may be directly deposited on the PCB <NUM> or it may be formed using a flow process.

Alternatively, the segmented LED emitter <NUM> may have multiple sections of the insulator <NUM> and multiple n-type contacts <NUM> extending in the x direction, resulting in any configurable number of pixels.

As seen in <FIG>, the substrate <NUM> may be removed from segmented LED emitter <NUM> shown in <FIG>. A laser liftoff or other epitaxial film separation may be used to remove the substrate <NUM>. Polishing or photo electrochemical etching may be applied to modify surface and optical properties of the n-type layer <NUM>.

As seen in <FIG>, a transparent conductive layer <NUM> may be formed on at least an upper surface of LED <NUM> The transparent conductive layer <NUM> may be composed of a transparent conductor such as antimony tin oxide (ATO), indium tin oxide (ITO), silver nanowires, or doped conductive graphene. The transparent conductive layer <NUM> may be deposited in separate, distinct lines, strings, pads, or blocks. Complex curved, circular, or winding layouts are possible.

The transparent conductive layer <NUM> may carry current from the n-type conductive line <NUM>, to the n-type contact <NUM>, to the conductive via <NUM>, to the n-type layer <NUM>. The conductive line <NUM> may carry current to the p-type contact <NUM> and into the p-type layer <NUM>. Each of the currents may meet at a junction of the n-type layer <NUM> and the p-type layer <NUM> to excite the active region <NUM> such that light is emitted from a pixel <NUM>.

Referring now to <FIG>, an example of an LED array <NUM> is shown. The LED array <NUM> may include a first LED <NUM> adjacent to a second LED <NUM>. The n-type layer <NUM> of the first LED <NUM> may be electrically coupled to the n-type layer <NUM> of the second LED <NUM>.

As shown in <FIG>, it may not be necessary for the second LED <NUM> to include the n-type via <NUM>, the n-type contact <NUM>, and the insulating lining <NUM>. In addition, an additional n-type conductive line <NUM> for the second LED <NUM> may not be needed. However, as shown in <FIG>, these optional features may be included in the second LED <NUM>.

As shown in <FIG> and <FIG>, the first LED <NUM> may be separated from the second LED <NUM> by a separation region <NUM>. The separation region <NUM> may be formed using conventional patterning, etching, and deposition techniques. For example, portions of the n-type layer <NUM> and the p-type layer <NUM> may be removed using an etching process to form a trench. The separation region <NUM> may be formed in the trench using a conventional deposition process. The separation region <NUM> may compose an insulating material, such as a dielectric.

<FIG> shows another example of the LED array <NUM> in which the second LED <NUM> is formed without the insulator <NUM> present in the first LED <NUM>. This may result in a pixel <NUM> having a larger width. In addition, <FIG> shows that the separation region <NUM> may be formed only through a portion of the n-type layer <NUM>.

<FIG> shows another example of the LED array <NUM> in which a trench <NUM> is formed in the n-type layer <NUM> to separate the first LED <NUM> and the second LED <NUM>. The trench <NUM> may be formed using a conventional etching process. The transparent conductive layer <NUM> may be conformal and may be formed in the trench <NUM>.

It should be noted that any combination of the first LED <NUM> and the second LED <NUM> may be used to form the LED array, and any combination of a separation region <NUM> and trench <NUM> may be used to define the first LED <NUM> and the second LED <NUM>.

<FIG> illustrates an overhead view of one or more LED arrays <NUM> using the transparent conductive layer <NUM> on top and the p-type conductive lines <NUM> on the bottom of individual LED <NUM>. The p-type conductive lines <NUM> may be laid out as columns, with each LED <NUM> connected. The conductive lines <NUM> may be laid out to extend over rows of LEDs <NUM>, with a connection to the PCB <NUM> made through the n-type layer <NUM>, the conductive via <NUM>, the n-type contact <NUM>, and the n-type conductive line <NUM>. In another example, the conductive lines <NUM> may be electrically connected to PCB <NUM> via wire bonds (not shown) or other suitable electrical contact or trace. Together, the conductive lines <NUM> and the p-type conductive lines <NUM> form a crossbar allowing activation (addressing) of selected pixels, lines of pixels, or blocks of pixels.

Referring now to <FIG>, a cross section view illustrating another example of the LED <NUM>. In this example, the conductive via <NUM> may be formed using the processes described below, but may be located on the outer edge <NUM> of the LED array <NUM>. An optional dielectric coating may be formed on the outer surface <NUM> of the conductive via. This arrangement may be used in any of the embodiments described herein.

Referring now to <FIG>, a flowchart illustrating a method of forming a device is shown. In step <NUM>, a conductive via may be formed in a first portion of an epitaxial layer. In step <NUM>, a first contact may be formed on a second portion of the epitaxial layer. The first portion and the second portion may be separated by an isolation region. In step <NUM>, a transparent conductive layer may be formed on the epitaxial layer.

As will be appreciated, various additions other modifications to the above-described LED architecture and process are possible. Pixels may be overlain with wavelength converting materials such as phosphors, quantum dots, or dyes. Multiple types and thicknesses of phosphors may be used. An LED combined with one or more wavelength converting materials may be used to create white light or monochromatic light of other colors. All or only a portion of the light emitted by the pixel may be converted by the wavelength converting material. Unconverted light may be part of the final spectrum of light, though it need not be. Examples of common devices include a blue-emitting pixel combined with a yellow-emitting phosphor, a blue-emitting pixel combined with green- and red-emitting phosphors, a UV-emitting pixel combined with blue- and yellow-emitting phosphors, and a UV-emitting pixel combined with blue-, green-, and red-emitting phosphors. The phosphors may be electrophoretically deposited on an pixel with application of a voltage to a particular transparent conductor string. Varying applied voltage duration will correspondingly vary amount and thickness of deposited phosphors. Alternatively, the pixel may be coated with the phosphor, using an organic binder to adhere the phosphor particles to the LED. Phosphors may be dispensed, screen printed, sprayed, molded, or laminated. Alternatively, for certain applications, a phosphor contained in glass, or a pre-formed sintered ceramic phosphor may be attached to the LED.

Microlenses or other primary or secondary optical elements (including reflectors, scattering elements, or absorbers) may be attached to each pixel or associated phosphor. A primary optic may be positioned over the entire array of pixels, and directly attached or mounted at a distance from the pixels in suitable packaging. Protective layers, transparent layers, thermal layers, or other packaging structures may be used as needed for specific applications.

<FIG> is a diagram of an LED device <NUM> in an example embodiment. The LED device <NUM> may include a substrate <NUM>, an active layer <NUM>, a wavelength converting layer <NUM>, and primary optic <NUM>. In other embodiments, an LED device may not include a wavelength converter layer and/or primary optics.

As shown in <FIG>, the active layer <NUM> may be adjacent to the substrate <NUM> and emits light when excited. Suitable materials used to form the substrate <NUM> and the active layer <NUM> include sapphire, SiC, GaN, Silicone and may more specifically be formed from a Ill-V semiconductors including, but not limited to, AIN, AlP, AlAs, AlSb, GaN, GaP, GaAs, GaSb, InN, InP, InAs, InSb, II-VI semiconductors including, but not limited to, ZnS, ZnSe, CdSe, CdTe, group IV semiconductors including, but not limited to Ge, Si, SiC, and mixtures or alloys thereof.

The wavelength converting layer <NUM> may be remote from, proximal to, or directly above active layer <NUM>. The active layer <NUM> emits light into the wavelength converting layer <NUM>. The wavelength converting layer <NUM> acts to further modify wavelength of the emitted light by the active layer <NUM>. LED devices that include a wavelength converting layer are often referred to as phosphor converted LEDs ("PCLED"). The wavelength converting layer <NUM> may include any luminescent material, such as, for example, phosphor particles in a transparent or translucent binder or matrix, or a ceramic phosphor element, which absorbs light of one wavelength and emits light of a different wavelength.

The primary optic <NUM> may be on or over one or more layers of the LED device <NUM> and allow light to pass from the active layer <NUM> and/or the wavelength converting layer <NUM> through the primary optic <NUM>. The primary optic <NUM> may be a lens or encapsulate configured to protect the one or more layers and to, at least in part, shape the output of the LED device <NUM>. Primary optic <NUM> may include transparent and/or semi-transparent material. In example embodiments, light via the primary optic may be emitted based on a Lambertian distribution pattern. It will be understood that one or more properties of the primary optic <NUM> may be modified to produce a light distribution pattern that is different than the Lambertian distribution pattern.

<FIG> shows a cross-sectional view of a lighting system <NUM> including an LED array <NUM> with pixels 201A, 201B, and 201C, as well as secondary optics <NUM> in an example embodiment. The LED array <NUM> includes pixels 201A, 201B, and 201C each including a respective wavelength converting layer 206B active layer 204B and a substrate 202B. The LED array <NUM> may be a monolithic LED array manufactured using wafer level processing techniques, a micro LED with sub-<NUM> micron dimensions, or the like. Pixels 201A, 201B, and 201C, in the LED array <NUM> may be formed using array segmentation, or alternatively using pick and place techniques.

The spaces <NUM> shown between one or more pixels 201A, 201B, and 201C of the LED devices 200B may include an air gap or may be filled by a material such as a metal material which may be a contact (e.g., n-contact).

The secondary optics <NUM> may include one or both of the lens <NUM> and waveguide <NUM>. It will be understood that although secondary optics are discussed in accordance with the example shown, in example embodiments, the secondary optics <NUM> may be used to spread the incoming light (diverging optics), or to gather incoming light into a collimated beam (collimating optics). In example embodiments, the waveguide <NUM> may be a concentrator and may have any applicable shape to concentrate light such as a parabolic shape, cone shape, beveled shape, or the like. The waveguide <NUM> may be coated with a dielectric material, a metallization layer, or the like used to reflect or redirect incident light. In alternative embodiments, a lighting system may not include one or more of the following: the wavelength converting layer 206B, the primary optics 208B, the waveguide <NUM> and the lens <NUM>.

Lens <NUM> may be formed form any applicable transparent material such as, but not limited to SiC, aluminum oxide, diamond, or the like or a combination thereof. Lens <NUM> may be used to modify the a beam of light input into the lens <NUM> such that an output beam from the lens <NUM> will efficiently meet a desired photometric specification. Additionally, lens <NUM> may serve one or more aesthetic purpose, such as by determining a lit and/or unlit appearance of the p 201A, 201B and/or 201C of the LED array <NUM>.

<FIG> is a top view of an electronics board <NUM> for an integrated LED lighting system according to one embodiment. In alternative embodiments, two or more electronics boards may be used for the LED lighting system. For example, the LED array may be on a separate electronics board, or the sensor module may be on a separate electronics board. In the illustrated example, the electronics board <NUM> includes a power module <NUM>, a sensor module <NUM>, a connectivity and control module <NUM> and an LED attach region <NUM> reserved for attachment of an LED array to a substrate <NUM>.

The substrate <NUM> may be any board capable of mechanically supporting, and providing electrical coupling to, electrical components, electronic components and/or electronic modules using conductive connecters, such as tracks, traces, pads, vias, and/or wires. The power module <NUM> may include electrical and/or electronic elements. In an example embodiment, the power module <NUM> includes an AC/DC conversion circuit, a DC/DC conversion circuit, a dimming circuit, and an LED driver circuit.

The sensor module <NUM> may include sensors needed for an application in which the LED array is to be implemented.

The connectivity and control module <NUM> may include the system microcontroller and any type of wired or wireless module configured to receive a control input from an external device.

The term module, as used herein, may refer to electrical and/or electronic components disposed on individual circuit boards that may be soldered to one or more electronics boards <NUM>. The term module may, however, also refer to electrical and/or electronic components that provide similar functionality, but which may be individually soldered to one or more circuit boards in a same region or in different regions.

<FIG> is a top view of the electronics board <NUM> with an LED array <NUM> attached to the substrate <NUM> at the LED device attach region <NUM> in one embodiment. The electronics board <NUM> together with the LED array <NUM> represents an LED system 400A. Additionally, the power module <NUM> receives a voltage input at Vin <NUM> and control signals from the connectivity and control module <NUM> over traces 418B, and provides drive signals to the LED array <NUM> over traces 418A. The LED array <NUM> is turned on and off via the drive signals from the power module <NUM>. In the embodiment shown in <FIG>, the connectivity and control module <NUM> receives sensor signals from the sensor module <NUM> over trace 418C.

<FIG> illustrates one embodiment of a two channel integrated LED lighting system with electronic components mounted on two surfaces of a circuit board <NUM>. As shown in <FIG>, an LED lighting system 400B includes a first surface 445A having inputs to receive dimmer signals and AC power signals and an AC/DC converter circuit <NUM> mounted on it. The LED system 400B includes a second surface 445B with the dimmer interface circuit <NUM>, DC-DC converter circuits 440A and 440B, a connectivity and control module <NUM> (a wireless module in this example) having a microcontroller <NUM>, and an LED array <NUM> mounted on it. The LED array <NUM> is driven by two independent channels 411A and 411B. In alternative embodiments, a single channel may be used to provide the drive signals to an LED array, or any number of multiple channels may be used to provide the drive signals to an LED array.

The LED array <NUM> may include two groups of LED devices. In an example embodiment, the LED devices of group A are electrically coupled to a first channel 411A and the LED devices of group B are electrically coupled to a second channel 411B. Each of the two DC-DC converters 440A and 440B may provide a respective drive current via single channels 411A and 411B, respectively, for driving a respective group of LEDs A and B in the LED array <NUM>. The LEDs in one of the groups of LEDs may be configured to emit light having a different color point than the LEDs in the second group of LEDs. Control of the composite color point of light emitted by the LED array <NUM> may be tuned within a range by controlling the current and/or duty cycle applied by the individual DC/DC converter circuits 440A and 440B via a single channel 411A and 411B, respectively. Although the embodiment shown in <FIG> does not include a sensor module (as described in <FIG> and <FIG>), an alternative embodiment may include a sensor module.

The illustrated LED lighting system 400B is an integrated system in which the LED array <NUM> and the circuitry for operating the LED array <NUM> are provided on a single electronics board. Connections between modules on the same surface of the circuit board <NUM> may be electrically coupled for exchanging, for example, voltages, currents, and control signals between modules, by surface or sub-surface interconnections, such as traces <NUM>, <NUM>, <NUM>, <NUM> and <NUM> or metallizations (not shown). Connections between modules on opposite surfaces of the circuit board <NUM> may be electrically coupled by through board interconnections, such as vias and metallizations (not shown).

According to embodiments, LED systems may be provided where an LED array is on a separate electronics board from the driver and control circuitry. According to other embodiments, a LED system may have the LED array together with some of the electronics on an electronics board separate from the driver circuit. For example, an LED system may include a power conversion module and an LED module located on a separate electronics board than the LED arrays.

According to embodiments, an LED system may include a multi-channel LED driver circuit. For example, an LED module may include embedded LED calibration and setting data and, for example, three groups of LEDs. One of ordinary skill in the art will recognize that any number of groups of LEDs may be used consistent with one or more applications. Individual LEDs within each group may be arranged in series or in parallel and the light having different color points may be provided. For example, warm white light may be provided by a first group of LEDs, a cool white light may be provided by a second group of LEDs, and a neutral white light may be provided by a third group.

<FIG> shows an example system <NUM> which includes an application platform <NUM>, LED systems <NUM> and <NUM>, and secondary optics <NUM> and <NUM>. The LED System <NUM> produces light beams <NUM> shown between arrows 561a and 561b. The LED System <NUM> may produce light beams <NUM> between arrows 562a and 562b. In the embodiment shown in <FIG>, the light emitted from LED system <NUM> passes through secondary optics <NUM>, and the light emitted from the LED System <NUM> passes through secondary optics <NUM>. In alternative embodiments, the light beams <NUM> and <NUM> do not pass through any secondary optics. The secondary optics may be or may include one or more light guides. The one or more light guides may be edge lit or may have an interior opening that defines an interior edge of the light guide. LED systems <NUM> and/or <NUM> may be inserted in the interior openings of the one or more light guides such that they inject light into the interior edge (interior opening light guide) or exterior edge (edge lit light guide) of the one or more light guides. LEDs in LED systems <NUM> and/or <NUM> may be arranged around the circumference of a base that is part of the light guide. According to an implementation, the base may be thermally conductive. According to an implementation, the base may be coupled to a heat-dissipating element that is disposed over the light guide. The heat-dissipating element may be arranged to receive heat generated by the LEDs via the thermally conductive base and dissipate the received heat. The one or more light guides may allow light emitted by LED systems <NUM> and <NUM> to be shaped in a desired manner such as, for example, with a gradient, a chamfered distribution, a narrow distribution, a wide distribution, an angular distribution, or the like.

In example embodiments, the system <NUM> may be a mobile phone of a camera flash system, indoor residential or commercial lighting, outdoor light such as street lighting, an automobile, a medical device, AR/VR devices, and robotic devices. The integrated LED lighting system shown in <FIG>, LED System 400A shown in <FIG>, illustrate LED systems <NUM> and <NUM> in example embodiments.

In example embodiments, the system <NUM> may be a mobile phone of a camera flash system, indoor residential or commercial lighting, outdoor light such as street lighting, an automobile, a medical device, AR/VR devices, and robotic devices. The LED System 400A shown in <FIG> and LED System 400B shown in <FIG> illustrate LED systems <NUM> and <NUM> in example embodiments.

The application platform <NUM> may provide power to the LED systems <NUM> and/or <NUM> via a power bus via line <NUM> or other applicable input, as discussed herein. Further, application platform <NUM> may provide input signals via line <NUM> for the operation of the LED system <NUM> and LED system <NUM>, which input may be based on a user input/preference, a sensed reading, a preprogrammed or autonomously determined output, or the like. One or more sensors may be internal or external to the housing of the application platform <NUM>.

In various embodiments, application platform <NUM> sensors and/or LED system <NUM> and/or <NUM> sensors may collect data such as visual data (e.g., LIDAR data, IR data, data collected via a camera, etc.), audio data, distance based data, movement data, environmental data, or the like or a combination thereof. The data may be related a physical item or entity such as an object, an individual, a vehicle, etc. For example, sensing equipment may collect object proximity data for an ADAS/AV based application, which may prioritize the detection and subsequent action based on the detection of a physical item or entity. The data may be collected based on emitting an optical signal by, for example, LED system <NUM> and/or <NUM>, such as an IR signal and collecting data based on the emitted optical signal. The data may be collected by a different component than the component that emits the optical signal for the data collection. Continuing the example, sensing equipment may be located on an automobile and may emit a beam using a vertical-cavity surface-emitting laser (VCSEL). The one or more sensors may sense a response to the emitted beam or any other applicable input.

In example embodiment, application platform <NUM> may represent an automobile and LED system <NUM> and LED system <NUM> may represent automobile headlights. In various embodiments, the system <NUM> may represent an automobile with steerable light beams where LEDs may be selectively activated to provide steerable light. For example, an array of LEDs may be used to define or project a shape or pattern or illuminate only selected sections of a roadway. In an example embodiment, Infrared cameras or detector pixels within LED systems <NUM> and/or <NUM> may be sensors that identify portions of a scene (roadway, pedestrian crossing, etc.) that require illumination.

Claim 1:
A light emitting diode (LED) array comprising:
a first LED (<NUM>) comprising an electrically conductive via (<NUM>) in a first portion in an epitaxial layer (<NUM>, <NUM>, <NUM>), a p-type contact (<NUM>) on a second portion of the epitaxial layer (<NUM>, <NUM>, <NUM>), the first portion and the second portion separated by an isolation region (<NUM>); and
a second LED (<NUM>) comprising the epitaxial layer (<NUM>, <NUM>, <NUM>), the second LED electrically coupled to the first LED through a transparent conductive layer (<NUM>);
wherein the epitaxial layer (<NUM>, <NUM>, <NUM>) comprises:
an n-type layer (<NUM>);
an active region (<NUM>); and
a p-type layer (<NUM>); and
wherein the isolation region (<NUM>) and the electrically conductive via (<NUM>) extend through the p-type layer (<NUM>), the active region (<NUM>), and only a portion of the n-type layer (<NUM>); wherein the first LED (<NUM>) is separated from the second LED (<NUM>) by a separation region (<NUM>); and
wherein the transparent conductive layer (<NUM>) electrically coupling the second LED (<NUM>) to the first LED (<NUM>) is on the n-type layer (<NUM>) of the epitaxial layer (<NUM>, <NUM>, <NUM>).