Substrate removal process for high light extraction LEDs
First Claim
1. A method for fabricating semiconductor based light emitting devices, comprising:
- providing a plurality of semiconductor layers on a substrate wafer, said plurality of semiconductor layers forming a plurality of light emitting devices, each of said light emitting devices comprising epitaxial layers and a lift-off layer between said substrate wafer and said epitaxial layers, said lift-off layer comprising a material from the group InGaN, AlInGaN, AlInGaAs;
providing a carrier comprising a junction diode on a first surface;
flip-chip mounting said light emitting devices on said first surface of said carrier such that said light emitting devices are sandwiched between said carrier and said substrate wafer;
exposing an n-type layer by removing said substrate wafer from said light emitting devices by exposing said lift-off layer to a solution and applying a light source, wherein said solution comprises KOH and water; and
separating said carrier into singulated portions to form light emitting devices separated from one another, with each of said light emitting devices mounted to a respective portion of said carrier.
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Accused Products
Abstract
A method for fabricating light emitting diode (LEDs) comprises providing a plurality of LEDs on a substrate wafer, each of which has an n-type and p-type layer of Group-III nitride material formed on a SiC substrate with the n-type layer sandwiched between the substrate and p-type layer. A conductive carrier is provided having a lateral surface to hold the LEDs. The LEDs are flip-chip mounted on the lateral surface of the conductive carrier. The SiC substrate is removed from the LEDs such that the n-type layer is the top-most layer. A respective contact is deposited on the n-type layer of each of the LEDs and the carrier is separated into portions such that each of the LEDs is separated from the others, with each of the LEDs mounted to a respective portion of said carrier.
89 Citations
30 Claims
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1. A method for fabricating semiconductor based light emitting devices, comprising:
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providing a plurality of semiconductor layers on a substrate wafer, said plurality of semiconductor layers forming a plurality of light emitting devices, each of said light emitting devices comprising epitaxial layers and a lift-off layer between said substrate wafer and said epitaxial layers, said lift-off layer comprising a material from the group InGaN, AlInGaN, AlInGaAs; providing a carrier comprising a junction diode on a first surface; flip-chip mounting said light emitting devices on said first surface of said carrier such that said light emitting devices are sandwiched between said carrier and said substrate wafer; exposing an n-type layer by removing said substrate wafer from said light emitting devices by exposing said lift-off layer to a solution and applying a light source, wherein said solution comprises KOH and water; and separating said carrier into singulated portions to form light emitting devices separated from one another, with each of said light emitting devices mounted to a respective portion of said carrier. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. A method for fabricating semiconductor based light emitting devices, comprising:
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providing a plurality of semiconductor layers on a substrate wafer, said plurality of semiconductor layers forming a plurality of light emitting devices, each of said light emitting devices comprising epitaxial layers; providing a carrier comprising a junction diode on a first surface; flip-chip mounting said light emitting devices on said first surface of said carrier such that said light emitting devices are sandwiched between said carrier and said substrate wafer; exposing an n-type layer by removing said substrate wafer from said light emitting devices; and separating said carrier into singulated portions to form light emitting devices separated from one another, with each of said light emitting devices mounted to a respective portion of said carrier; wherein each of said semiconductor based light emitting devices further comprises a lift-off layer between said substrate wafer and epitaxial layers, wherein said removing of said substrate wafer from each of said light emitting devices comprises exposing said lift-off layer to a solution and applying a light source, the combination of said solution and light source causing only said lift-off layer to etch, wherein said lift-off layer comprises a material from the group InGaN, AlInGaN and AlInGaAs, and wherein said solution comprises KOH and water and said light source has an approximate 400 nanometer (nm) wavelength.
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22. A method for fabricating light emitting diodes (LEDs), comprising:
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providing a plurality of semiconductor layers on a SiC substrate wafer, said semiconductor layers forming a plurality of LEDs, each of said LEDs having an n-type layer and a p-type layer, said n-type layer sandwiched between said SiC substrate wafer and said p-type layer; providing a lift-off layer between said SiC substrate wafer and said n-type layer; disposing at least first and second reflective metal layers on said plurality of semiconductor layers; providing a carrier having a lateral surface to hold said LEDs; flip-chip mounting said LEDs on said carrier'"'"'s lateral surface such that said LEDs are sandwiched between said SiC substrate wafer and said carrier; exposing said n-type layer by removing said SiC substrate wafer from said LEDs by removing said lift-off layer, wherein said lift-off layer is removed by exposing it to an etch solution and applying a light source, said solution comprising KOH and water and said light source having an approximate 400 nanometer (nm) wavelength; depositing a respective contact on said n-type layer of each of said LEDs; and separating said carrier into singulated portions, with each of said LEDs mounted to a respective portion of said carrier. - View Dependent Claims (23, 24, 25, 26)
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27. A method for fabricating semiconductor based light emitting devices, comprising:
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providing a lift-off layer on a substrate wafer; providing a plurality of semiconductor layers on said substrate wafer with said lift-off layer, said plurality of semiconductor layers forming a plurality of light emitting devices, each of said light emitting devices comprising epitaxial layers; providing a carrier; flip-chip mounting said substrate wafer on said carrier such that said semiconductor layers are sandwiched between said carrier and said substrate wafer; removing said substrate wafer from said semiconductor layers by removing said lift-off layer, wherein said removing of said lift-off layer comprises exposing said lift-off layer to a photo electrochemical etch, wherein said removing of said lift-off layer comprises a combination of exposing said lift-off layer to a solution and applying a light source, the combination of said solution and light source causing said lift-off layer to etch without etching the surrounding semiconductor layers, wherein said lift-off layer comprises a material from the group InGaN, AlInGaN and AlInGaAs, and wherein said solution comprises KOH and water and said light source has an approximate 400 nanometer (nm) wavelength; and separating said semiconductor layers into singulated portions to form light emitting devices separated from one another. - View Dependent Claims (28)
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29. A method for fabricating semiconductor based light emitting devices, comprising:
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providing a lift-off layer on a substrate wafer; providing a plurality of semiconductor layers on said substrate wafer with said lift-off layer, said plurality of semiconductor layers forming a plurality of light emitting devices, each of said light emitting devices comprising epitaxial layers; providing a carrier; flip-chip mounting said substrate wafer on said carrier such that said semiconductor layers are sandwiched between said carrier and said substrate wafer; removing said substrate wafer from said semiconductor layers by removing said lift-off layer, wherein said removing of said lift-off layer comprises exposing said lift-off layer to a photo electrochemical etch, wherein said removing of said lift-off layer comprises a combination of exposing said lift-off layer to a solution and applying a light source, the combination of said solution and light source causing said lift-off layer to etch without etching the surrounding semiconductor layers; and separating said semiconductor layers into singulated portions to form light emitting devices separated from one another; wherein said substrate comprises SiC, said epitaxial structure comprises GaN, and said lift-off layer comprises a material from the group InGaN, AlInGaN and AlInGaAs, wherein removing said lift-off layer comprises illuminating said device with laser light having a wavelength in the range of approximately 390 to 450 nm. - View Dependent Claims (30)
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Specification