Patent ID: 12191298

DETAILED DESCRIPTION

Specific details of several embodiments of solid state lights (“SSLs”) and associated methods of manufacturing SSLs are described below. The term “SSL” generally refers to “solid state light” and/or “solid state lighting device” according to the context in which it is used. The term “SSE” generally refers to solid state components that convert electrical energy into electromagnetic radiation in the visible, ultraviolet, infrared and/or other spectra. SSEs include semiconductor light-emitting diodes (“LEDs”), polymer light-emitting diodes (“PLEDs”), organic light-emitting diodes (“OLEDs”), or other types of solid state devices that convert electrical energy into electromagnetic radiation in a desired spectrum. The term “phosphor” generally refers to a material that can continue emitting light after exposure to energy (e.g., electrons and/or photons). Additionally, packaged SSLs and methods of manufacturing SSL assemblies are specifically described below to provide an enabling disclosure, but the package and methods can be applied to other SSLs as well. A person skilled in the relevant art will understand that the new technology may have additional embodiments and that the new technology may be practiced without several of the details of the embodiments described below with reference toFIGS.2-6.

FIG.2illustrates a back-to-back SSL200configured in accordance with several embodiments of the new technology. The SSL200can include a carrier substrate202having a plurality of through substrate interconnects (TSIs)208, e.g., two TSIs (identified individually as a first TSI208aand a second TSI208b). The SSL200can further include a plurality of SSEs210, e.g., two SSEs (identified individually as a first SSE210aand a second SSE210b) electrically coupled to the TSIs208. In the illustrated embodiment, the carrier substrate202includes a first surface204and a second surface206opposite the first surface204with the TSIs208extending from the first surface204to the second surface206. In the SSL200illustrated inFIG.2, the SSEs210each have a front side212and a back side214opposite the front side212. The back side214of the first SSE210acan be proximate (e.g., the closest surface of the SSE210a) to the first surface204of the carrier substrate202, and the back side214of the second SSE210bcan be proximate to the second surface206of the carrier substrate202. The first and second SSEs210a-bcan be electrically coupled to both the first TSI208aand the second TSI208b. In further embodiments, the SSL200can include additional SSEs210proximate to the first surface204and/or the second surface206of the carrier substrate202with corresponding TSIs208electrically coupled to the SSEs210.

The individual SSEs210can include a first semiconductor material218having a first contact226, an active region220, and a second semiconductor material222having a second contact228. The first semiconductor material218can be an N-type semiconductor material, such as N-type gallium nitride (“N-GaN”), and the second semiconductor material222can be a P-type semiconductor material, such as P-type gallium nitride (“P-GaN”). The active region220can be indium gallium nitride (“InGaN”). The first semiconductor material218, active region220, and second semiconductor material222can be deposited sequentially using chemical vapor deposition (“CVD”), physical vapor deposition (“PVD”), atomic layer deposition (“ALD”), plating, or other techniques known in the semiconductor fabrication arts. In the embodiment illustrated inFIG.2, the first semiconductor material218is at the front side212of each SSE210, and the second semiconductor material222is at the back side214. In other embodiments, the semiconductor materials can be reversed, such that the first semiconductor material218is at the back side214and the second semiconductor material222is at the front side212.

The SSEs210can be configured to emit light in the visible spectrum (e.g., from about 390 nm to about 750 nm), in the infrared spectrum (e.g., from about 1050 nm to about 1550 nm), and/or in other suitable spectra. In some embodiments, the SSEs210can emit light having approximately equivalent wavelengths such that the SSL200emits a uniform color of light. In other embodiments, the first SSE210acan emit light having a first wavelength and the second SSE210bcan emit light having a second wavelength different from the first wavelength such that the SSL200can emit more than one color of light and/or the wavelengths can be combined to create a different color of light.

In some embodiments, the SSEs210can optionally include a reflective material242attached with a transparent electrically conductive material (not shown) to the back side214of one or more SSEs210. The reflective material242can be silver (Ag), gold (Au), copper (Cu), aluminum (Al), or any other suitable material that reflects light emitted from the active region220so as to redirect the light back through second semiconductor material222, the active region220, and the first semiconductor material218. The reflective material242can have a high thermal conductivity. The reflective material242can also be selected based on the color of light it reflects. For example, silver generally does not alter the color of the reflected light. Gold, copper or other reflective, colored materials can affect the color of the light and can accordingly be selected to produce a desired color for the light emitted by the SSL200. The transparent conductive material can be indium tin oxide (ITO) or any other suitable material that is transparent, electrically conductive, and adheres the reflective material to the second semiconductor material222. The transparent conductive material and reflective material242can be deposited using CVD, PVD, ALD, plating, or other techniques known in the semiconductor fabrication arts.

To obtain certain colors of light from the SSL200, a converter material216(e.g., phosphor, shown in dashed lines) can be placed over the SSL200such that light from the SSEs210irradiates energized particles (e.g., electrons and/or photons) in the converter material216. The irradiated converter material216then emits light of a certain quality (e.g., color, warmth, intensity, etc.). Alternatively, the converter material216can be spaced apart from the SSL200in any other location that is irradiated by the SSL200. In one embodiment, the converter material216can include a phosphor containing cerium (III)-doped yttrium aluminum garnet (YAG) at a particular concentration for emitting a range of colors from green to yellow and to red under photoluminescence. In other embodiments, the converter material216can include neodymium-doped YAG, neodymium-chromium double-doped YAG, erbium-doped YAG, ytterbium-doped YAG, neodymium-cerium double-doped YAG, holmium-chromium-thulium triple-doped YAG, thulium-doped YAG, chromium (IV)-doped YAG, dysprosium-doped YAG, samarium-doped YAG, terbium-doped YAG, and/or other suitable wavelength conversion materials. In additional embodiments, different converter materials216can be placed over the first SSE210aand the second SSE210bso the SSL200can emit multiple, different qualities of light. In further embodiments, the converter material216can differ on each surface (e.g., the first surface204, the second surface206, etc.) of the carrier substrate202, such that the SSL200emits differing qualities of light from different surfaces. Each surface of the carrier substrate202can provide a natural barrier for differing converter materials216, thereby simplifying the placement of different converter materials216on the SSE200.

The carrier substrate202can comprise an aluminum nitride (ALN) material. Aluminum nitride is an electrically insulating ceramic with a high thermal conductivity. Thus, embodiments of SSL200including the aluminum nitride carrier substrate202can efficiently transfer heat from the SSEs210without interfering with the electrical properties of contacts, TSIs, leads, and/or other electrical features. The cooling effect of aluminum nitride is especially advantageous for back-to-back SSLs, such as the SSL200, because the addition of SSEs210on multiple surfaces of the carrier substrate202can otherwise impede heat transfer from the SSL200, which can degrade heat sensitive components. In other embodiments, the carrier substrate can comprise another suitable dielectric material (e.g., silicon).

The carrier substrate202can further include a plurality of leads232for providing electrical connections to the SSEs210. For example, the carrier substrate202illustrated inFIG.2includes a first lead232acoupled to a negative potential and a second lead232bcoupled to a positive potential. In further embodiments, the potentials can be reversed such that the first lead232acouples to the positive potential and the second lead232bcouples to the negative potential. In still further embodiments, the carrier substrate202can include additional leads232to provide an electrical connection for additional SSEs210.

The plurality of TSIs208extending through the carrier substrate202can include one or more electrically conductive materials. For example, the conductive material can comprise copper (Cu), aluminum (Al), tungsten (W), and/or other suitable substances or alloys. The TSIs208can further include a thermally conductive material that transfers heat away from the SSEs210to provide cooling for the SSEs210. The TSIs208can be any shape and size suitable for electrical and/or thermal conductivity. In some embodiments, the TSIs208can be formed by removing portions of the carrier substrate202using etching, laser drilling, or other suitable techniques known to those skilled in the art. The resultant apertures in the carrier substrate202can be at least partially filled with the electrically conductive material(s) using plating, physical vapor deposition (PVD), chemical vapor deposition (CVD), or other suitable techniques known to those skilled in the art. If necessary, a portion of the carrier substrate202can be removed (e.g., by backgrinding) to form the TSIs208. In other embodiments, the carrier substrate202can include pre-formed apertures that can be at least partially filled with the electrically conductive material(s). The TSIs208can be formed by removing a portion of the carrier substrate202using backgrinding or other techniques known in the art.

The TSIs208can provide an electrical connection between the SSEs210and the leads232. InFIG.2, for example, the first TSI208acan be coupled to the first lead232aand the second TSI208bcan be coupled to the second lead232b, such that the first TSI208acan be a negative terminal and the second TSI208bcan be a positive terminal. The exposed ends of the TSIs208at the first surface204of the carrier substrate202can be coupled to the first SSE210a, and the exposed ends of the TSIs208at the second surface206of the carrier substrate202can be coupled to the second SSE210b. In the embodiment illustrated inFIG.2, the second semiconductor material222and the active region220of the each SSE210expose the first contact226on the first semiconductor material218. The SSEs210having this configuration can include one or more conductive members230that couple the first contacts226to the exposed ends of the first TSI208aand/or the second contacts228to the exposed ends of the second TSI208b. In the embodiment illustrated inFIG.2, the conductive members can be solder balls comprising copper (Cu), aluminum (Al), tungsten (W), and/or other suitable electrically conductive substances or alloys. In alternative embodiments, the first and second contacts226and228can be coupled to the corresponding TSIs208using different techniques known in the art (e.g., surface mounting, wirebonding, etc.).

In operation, the SSEs210convert electrical energy into electromagnetic radiation in a desired spectrum causing the first SSE210ato emit light away from the first surface204of the carrier substrate202and the second SSE210bto emit light away from the second surface206. Thus, unlike conventional SSLs that emit light from a single plane, SSLs in accordance with the new technology (e.g., the SSL200) can emit light from a plurality of planes. This can increase the intensity of illumination and/or create a wide angle of illumination (e.g., 360° of illumination). Additionally, since SSLs in accordance with the new technology utilize more than one surface of the associated carrier substrates, the SSLs can have a smaller footprint and/or a more compact size in the vertical and lateral directions than conventional SSLs that must be combined to create somewhat similar features. Thus, SSLs in accordance with the new technology can be particularly advantageous where three dimensional illumination is required (e.g., light posts) and/or where a high intensity of light in a small space (e.g., cell phones) is desired.

In the embodiment illustrated inFIG.2, the first and second SSEs210a-bare proximate to the first surface204and the second surface206of the carrier substrate202and have an angle of incidence of approximately 180°. In alternative embodiments, the SSEs210can be on more than two surfaces of the carrier substrate202and/or can have a smaller or larger angle of incidence between the SSEs210. In one embodiment, for example, the carrier substrate202can be a hexagonal prism and include one or more SSEs210on each of its eight surfaces.

FIG.3is a partially schematic cross-sectional view of a back-to-back SSL300in accordance with several embodiments of the new technology. Several features of the SSL300are generally similar to the features ofFIG.2and are accordingly not described in detail below. The SSEs210shown inFIG.3include a wirebond234between the carrier substrate202and the SSEs210. For example, in the illustrated embodiment, the first contacts226can be on the front surfaces212of each corresponding SSE210and the first TSI208acan be laterally spaced apart from the SSEs210, such that each first contact226can be electrically coupled to the corresponding exposed end of the first TSI208awith the corresponding wirebond234. The second contacts228can be surface mounted to the corresponding exposed ends of the second TSI208b. In other embodiments, the first and second contacts226and228can be electrically coupled to the TSIs208using other suitable methods known to those skilled in the art. In the configuration illustrated inFIG.3, only one contact (e.g., the second contact228) need be aligned with a TSI208to form an electrical connection, thereby easing the alignment requirements during manufacturing.

FIG.4is a partially schematic cross-sectional view of a back-to-back SSL400in accordance with several embodiments of the new technology. Several features of the SSL400are generally similar to the features ofFIGS.2-3and are accordingly not described in detail below. InFIG.4, the first contacts226are buried contacts in the first semiconductor materials218of the first and second SSEs210. The SSL400can include connectors236extending from each end of the first TSI208ato the corresponding first contact226that electrically couple the two components. The connector236can comprise copper (Cu), aluminum (Al), gold (Au), tungsten (W), and/or other suitable conductive materials. The connector236can be at least partially surrounded by a dielectric material238, such that the connector236is electrically isolated from portions of the SSE210other than the first contact226(e.g., the second semiconductor material222and the active material220). In some embodiments, the connector236and the TSI208can be integrally formed. Advantageously, the buried contact allows the SSEs210to sit flush with the carrier substrate202, thereby giving the SSL400a more compact size in the vertical and lateral directions.

FIG.5is a partially schematic cross-sectional view of a back-to-back SSL500in accordance with several embodiments of the new technology. Several features of the SSL500are generally similar to the features ofFIGS.2-4and are accordingly not described in detail below. InFIG.5, the carrier substrate202further includes a conductive core240comprising a highly thermally conductive material, such as aluminum (Al), gold (Au), copper (Cu), and/or another suitable materials. In the illustrated embodiment, the conductive core240is electrically isolated from the TSIs208, the SSEs210, the leads232, and/or other electrical features. The conductive core240can increase the transfer of heat away from SSEs210to provide cooling for the SSL500. In some embodiments, the SSL500can include a carrier substrate comprising an aluminum nitride material and the conductive core240to provide exceptional cooling effects.

FIG.6is a partially schematic cross-sectional view of a rotatable back-to-back SSL600in accordance with several embodiments of the new technology. The SSL600can include several features generally similar to any of the above SSLs described inFIGS.2-5, such as the carrier substrate202and the plurality of SSEs210. The SSL600can further include a rotation device650configured to rotate the SSEs210around one or more axis, such as the axis Y-Y. In one embodiment, the rotation device650can spin the SSEs210at a first speed such that the SSL600emulates a blinking light. For example, each SSE210can emit a stream of light and the rotation device650can spin the SSL600at a first speed, such that the human eye can perceive the intermittent breaks in the light as the SSL600rotates to expose surfaces of the carrier substrate202without light emitted by the SSEs210. In another embodiment, the rotation device650can spin the SSL600at a second speed higher than the first speed, such that the SSL600emulates a generally constant stream of light at a point spaced apart from the SSL600. For example, a generally constant stream of light means the rotation device650can spin the SSL600at a speed that prevents the human eye from perceiving surfaces of the carrier substrate202without the SSEs210. In some embodiments, the first SSE210acan emit a first color of light and the second SSE210bcan emit a second color of light different than the first color, such that the first and second colors of light can combine to emit a third color of light when the rotation device650spins the SSL600at the second speed. In further embodiments, the SSEs can emit more than two colors of light. In still further embodiments, the SSL600can include additional SSEs on one or more surfaces of the carrier substrate, and/or the rotation device650can spin the SSL600at varying speeds around one or more axis.

From the foregoing, it will be appreciated that specific embodiments of the present technology have been described herein for purposes of illustration, but that various modifications may be made without deviating from the technology. For example, the embodiments illustrated inFIGS.2-6include through substrate interconnects having a straight trajectory. However, other embodiments of the new technology can include through substrate interconnects having angled, curved, and/or other trajectories that can electrically connect SSEs on different surfaces of carrier substrates. Certain aspects of the new technology described in the context of particular embodiments may be combined or eliminated in other embodiments. For example, the SSL ofFIG.6can include any of the foregoing SSL arrangements. Additionally, an SSL in accordance with the technology can include a combination of SSEs having any one of the forgoing configurations. For example, an SSL can include a SSE as illustrated inFIG.2and another SSE as illustrated inFIG.4. Further, while advantages associated with certain embodiments of the new technology have been described in the context of those embodiments, other embodiments may also exhibit such advantages, and not all embodiments need necessarily exhibit such advantages to fall within the scope of the technology. Accordingly, the disclosure and associated technology can encompass other embodiments not expressly shown or described herein.