Patent number 8604491 is assigned to
The following quote was obtained by the news editors from the background information supplied by the inventors: "A Light-Emitting Diode (LED), as used herein, is a semiconductor light source for generating a light at a specified wavelength or a range of wavelengths. LEDs are traditionally used for indicator lamps, and are increasingly used for displays. An LED emits light when a voltage is applied across a p-n junction formed by oppositely doping semiconductor compound layers. Different wavelengths of light can be generated using different materials by varying the bandgaps of the semiconductor layers and by fabricating an active layer within the p-n junction. Additionally, an optional phosphor material changes the properties of light generated by the LED.
"Traditionally, LEDs are made by growing a plurality of light-emitting structures on a growth substrate. The light-emitting structures along with the underlying growth substrate are separated into individual LED dies. At some point before or after the separation, electrodes or conductive pads are added to the each of the LED dies to allow the conduction of electricity across the structure. The light-emitting structure and the wafer on which the light-emitting structure is formed is referred to herein as an epi wafer. LED dies are then packaged by adding a package substrate, optional phosphor material, and optics such as lens and reflectors to become an optical emitter.
"The LED die is electrically connected to circuitry on the package substrate in a number of ways. One conventional connection method involves attaching the growth substrate portion of the die to the package substrate, and forming electrode pads that are connected to the p-type semiconductor layer and the n-type semiconductor layer in the light-emitting structure on the die, and then bond wiring from the electrode pads to contact pads on the package substrate. When wire bonds are used at both the p-contacts and n-contacts, light may escape from the sides of the LEDs, which is generally undesirable. Also, wire bonding uses space within the package footprint, and this space is generally viewed as wasted. Thus, wire bonding approaches in one aspect can be inefficient.
"Another conventional connection method involves inverting the LED die and using solder bumps to connect the electrode pads on the light-emitting structure directly to the package substrate, commonly referred to as a flip chip. However, flip chip processes at this level of LED manufacturing can be costly and inconvenient to implement. Yet another conventional connection method involves using hybrid connectors. One semiconductor layer, for example the p-type layer, may be wired bonded to the package substrate while the other layer (n-type layer) may be soldered to the package substrate.
"Therefore, while existing methods of manufacturing the LED devices have been generally adequate for their intended purposes, they have not been entirely satisfactory in every aspect."
In addition to the background information obtained for this patent, VerticalNews journalists also obtained the inventors' summary information for this patent: "One of the broader forms of the present disclosure involves a vertical Light Emitting Diode (LED) device includes an epi structure with a first-type-doped portion, a second-type-doped portion, and a quantum well structure between the first-type-doped and second-type-doped portions and a semi-insulated carrier structure with a plurality of conductive contact pads in electrical contact with the epi structure and a plurality of bonding pads on a side of the carrier structure distal the epi structure, in which the conductive contact pads are in electrical communication with the bonding pads using at least one of vias and a Redistribution Layer (RDL). The vertical LED device further includes a first insulating film on a side of the carrier structure proximal the epi structure and a second insulating film on a side of the carrier structure distal the epi structure.
"Another one of the broader forms of the present disclosure involves a semiconductor structure includes an epi wafer and a carrier wafer with a plurality of conductive contact pads in electrical communication with the epi wafer. The epi wafer includes a first-type-doped portion and a second-type-doped portion. The first-type-doped portion is distal the carrier wafer, and the second-type-doped portion is proximal the carrier wafer. The semiconductor structure includes a plurality of Light-Emitting Diode (LED) dies, each of the LED dies having a first contact pad on a side of the carrier wafer distal the epi wafer, the first contact pad in electrical contact with the first-type-doped portion through an interconnect in the epi wafer and a first via in the carrier wafer, and a second contact pad on the side of the carrier wafer distal the epi wafer. The second contact pad is in electrical contact with the second-type-doped portion through a second via in the carrier wafer.
"Still another one of the broader forms of the present disclosure involves a wafer-level process for manufacturing a semiconductor structure that has an epi wafer coupled to a carrier wafer, where the semiconductor structure has a plurality of Light Emitting Diode (LED) dies, the process including for each of the dies: forming a first contact pad on a second-type-doped portion of the epi wafer, the epi wafer also having a first-type-doped portion. The process further comprising for each of the dies: bonding the carrier wafer and the epi wafer so that the first contact pad electrically contacts a second contact pad on a side of the carrier wafer distal the epi wafer, the first contact pad electrically contacting the second contact pad by a first via through the carrier wafer, and forming an interconnect through the epi wafer, the interconnect electrically coupling the first-type-doped portion to a third contact pad on the side of the carrier wafer distal the epi wafer."
URL and more information on this patent, see: Yu, Chih-Kuang; Kuo, Hung-Yi. Wafer Level Photonic Device Die Structure and Method of Making the Same. U.S. Patent Number 8604491, filed
Keywords for this news article include: Electronics, Semiconductor, Light-emitting Diode, Electrical Communication,
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