High temperature gold-free wafer bonding for light emitting diodes
First Claim
1. A method of manufacture comprising:
- (a) wafer bonding a carrier wafer structure to a device wafer structure by melting a bond metal disposed between the carrier wafer structure and the device wafer structure, wherein the device wafer structure comprises a silicon substrate and an epitaxial Light Emitting Diode (LED) structure formed on the silicon substrate, wherein the epitaxial LED structure comprises an n-type layer, a p-type layer, and an active layer disposed between the n-type layer and the p-type layer, wherein the active layer comprises an amount of indium, wherein the carrier wafer structure comprises a carrier, wherein the bond metal layer includes substantially no gold and wherein the wafer bonding of (a) results in a wafer bonded structure;
(b) after (a) removing the silicon substrate from the wafer bonded structure;
(c) after (b) forming first and second electrodes, the first electrode being in contact with the n-type layer, the second electrode being in contact with the p-type layer; and
(d) singulating the wafer bonded structure thereby forming an LED device,wherein the bond metal comprises aluminum and silicon.
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Accused Products
Abstract
A vertical GaN-based LED is made by growing an epitaxial LED structure on a silicon wafer. A silver layer is added and annealed to withstand >450° C. temperatures. A barrier layer (e.g., Ni/Ti) is provided that is effective for five minutes at >450° C. at preventing bond metal from diffusing into the silver. The resulting device wafer structure is then wafer bonded to a carrier wafer structure using a high temperature bond metal (e.g., AlGe) that melts at >380° C. After wafer bonding, the silicon is removed, gold-free electrodes (e.g., Al) are added, and the structure is singulated. High temperature solder (e.g., ZnAl) that is compatible with the electrode metal is used for die attach. Die attach occurs at >380° C. for ten seconds without melting the bond metal or otherwise damaging the device. The entire LED contains no gold, and consequently is manufacturable in a high-volume gold-free semiconductor fabrication facility.
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Citations
25 Claims
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1. A method of manufacture comprising:
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(a) wafer bonding a carrier wafer structure to a device wafer structure by melting a bond metal disposed between the carrier wafer structure and the device wafer structure, wherein the device wafer structure comprises a silicon substrate and an epitaxial Light Emitting Diode (LED) structure formed on the silicon substrate, wherein the epitaxial LED structure comprises an n-type layer, a p-type layer, and an active layer disposed between the n-type layer and the p-type layer, wherein the active layer comprises an amount of indium, wherein the carrier wafer structure comprises a carrier, wherein the bond metal layer includes substantially no gold and wherein the wafer bonding of (a) results in a wafer bonded structure; (b) after (a) removing the silicon substrate from the wafer bonded structure; (c) after (b) forming first and second electrodes, the first electrode being in contact with the n-type layer, the second electrode being in contact with the p-type layer; and (d) singulating the wafer bonded structure thereby forming an LED device, wherein the bond metal comprises aluminum and silicon. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method of manufacture comprising:
(a) wafer bonding a carrier wafer structure to a device wafer structure by melting a bond metal disposed between the carrier wafer structure and the device wafer structure, wherein the device wafer structure comprises an epitaxial Light Emitting Diode (LED) structure, wherein the epitaxial LED structure comprises an n-type layer, a p-type layer, and an active layer disposed between the n-type layer and the p-type layer, wherein the active layer comprises an amount of indium, wherein the carrier wafer structure comprises a carrier, and wherein the bond metal comprises aluminum and germanium. - View Dependent Claims (11)
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12. A method of manufacture comprising:
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(a) wafer bonding a carrier wafer structure to a device wafer structure by melting a bond metal disposed between the carrier wafer structure and the device wafer structure, wherein the device wafer structure comprises a silicon substrate and an epitaxial Light Emitting Diode (LED) structure formed on the silicon substrate, wherein the epitaxial LED structure comprises an n-type layer, a p-type layer, and an active layer disposed between the n-type layer and the p-type layer, wherein the active layer comprises an amount of indium, wherein the carrier wafer structure comprises a carrier, wherein the bond metal layer includes substantially no gold and wherein the wafer bonding of (a) results in a wafer bonded structure; (b) after (a) removing the silicon substrate from the wafer bonded structure; (c) after (b) forming first and second electrodes, the first electrode being in contact with the n-type layer, the second electrode being in contact with the p-type layer; and (d) singulating the wafer bonded structure thereby forming an LED device, wherein the bond metal comprises an aluminum sublayer and a germanium sublayer, wherein the aluminum sublayer at the time of the wafer bonding of (a) is a part of the device wafer structure, wherein the germanium sublayer at the time of the wafer bonding of (a) is a part of the carrier wafer structure, and wherein the aluminum sublayer and the germanium sublayer fuse together during the wafer bonding of (a). - View Dependent Claims (13, 14, 15, 16, 17, 18, 19)
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20. A method of manufacture comprising:
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(a) wafer bonding a carrier wafer structure to a device wafer structure by melting a bond metal disposed between the carrier wafer structure and the device wafer structure, wherein the device wafer structure comprises a silicon substrate and an epitaxial Light Emitting Diode (LED) structure formed on the silicon substrate, wherein the epitaxial LED structure comprises an n-type layer, a p-type layer, and an active layer disposed between the n-type layer and the p-type layer, wherein the active layer comprises an amount of indium, wherein the carrier wafer structure comprises a carrier, wherein the bond metal layer includes substantially no gold, and wherein the wafer bonding of (a) results in a wafer bonded structure; (b) after (a) removing the silicon substrate from the wafer bonded structure; (c) after (b) forming first and second electrodes, the first electrode being in contact with the n-type layer, the second electrode being in contact with the p-type layer; (d) singulating the wafer bonded structure thereby forming an LED device; (e) attaching the LED device to a metal surface by melting an amount of solder, wherein the solder has a melting temperature, wherein the melting temperature of the solder is lower than a melting temperature of the bond metal, wherein the bond metal comprises aluminum and germanium. - View Dependent Claims (21, 22, 23, 24, 25)
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Specification