EP0616376A1
Expired / Lapsed
EP
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Wafer bonding of light emitting diode layers
Assignee: HP Inc
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Filing: 1994-01-21
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Granted: —
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Expires: 2014-01-21
Abstract
Abstract A method of forming a light emitting diode (LED) includes providing a temporary growth substrate (30) that is selected for compatibility with fabricating LED layers (32, 34, 36 and 38) having desired mechanical characteristics. For example, lattice matching is an important consideration. LED layers are then grown on the temporary growth substrate. High crystal quality is thereby achieved, whereafter the temporary growth substrate can be removed. A second substrate (42) is bonded to the LED layers utilizing a wafer bonding technique. The second substrate is selected for optical properties, rather than mechanical properties. Preferably, the second substrate is optically transparent and electrically conductive and the wafer bonding technique is carried out to achieve a low resistance interface between the second substrate and the LED layers. Wafer bonding can also be carried out to provide passivation or light-reflection or to define current flow.
Inventors
- 👤 Fred A. Kish
- 👤 Frank M. Steranka
- 👤 Dennis C. Defever
- 👤 Virginia M. Robbins
- 👤 John Uebbing
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-03 18:38
CPC Classifications
H; H10; H10H; H10H20/00; H10H20/01; H10H20/011; H10H20/012; H10H20/0125; H10H20/013; H10H20/018; H10H20/80; H10H20/81; H10H20/8215; H10H20/822; H10H20/824; H10W; H10W90/00; H10H20/816; H10H20/8162
Claims Analysis
Total Claims: 24
Claim 1
Independent Claim
85 words
A method of forming a light emitting diode (LED) comprising: selecting a first material having properties compatible with fabricating LED layers (32, 34, 36 and 38) having desired mechanical characteristics; providing a first substrate (30) made of the selected first material; fabricating the LED layers on the first substrate, thereby forming an LED structure (40); selecting an optically transparent material compatible with enhancing performance of the LED structure; and wafer bonding a transparent layer (42) of the selected optically transparent material to the LED layers.
Claim 2
Dependent Claim
51 words
The method of claim 1 wherein fabricating the LED layer is a step of epitaxially growing a plurality of layers (32, 34, 36 and 38) on the first substrate (30), the first material being a selection of a material to provide a lattice compatible with epitaxially growing the plurality of layers.
Claim 3
Dependent Claim
14 words
The method of claim 1 or 2 further comprising removing the first substrate (30).
Claim 4
Dependent Claim
50 words
The method of claim 3 wherein removing the first substrate (30) is a step performed prior to wafer bonding the transparent layer (42), the wafer bonding being a step of wafer bonding a transparent substrate to a side of the LED structure (40) from which the first substrate is removed.
Claim 5
Dependent Claim
48 words
The method of claim 1 wherein wafer bonding the transparent layer (42) to the LED structure (40) is a step performed at elevated temperatures to obtain a low resistance electrical connection, including elevating the temperature to provide softening of the layers (32 and 42) to be wafer bonded.
Claim 6
Dependent Claim
34 words
The method of claim 5 wherein wafer bonding is a step including applying pressure to the layers (32 and 42) to be wafer bonded to achieve conformity of the layers to be wafer bonded.
Claim 7
Dependent Claim
61 words
The method of claim 1 wherein at least one of the steps of fabricating the LED layers (32, 34, 36 and 38) and selecting the optically transparent material is a step of selecting one of an In-bearing compound, an Hg-bearing compound, a Cd-bearing compound and a Zn-bearing compound at an interface of the layers (32 and 42) to be wafer bonded.
Claim 8
Independent Claim
145 words
A method of forming a light emitting diode (LED) comprising: providing a temporary growth substrate (30) having a lattice compatible with epitaxially growing LED layers (32, 34, 36 and 38); epitaxially growing a lamination of LED layers on the growth substrate, the lamination having a first side (38) and having a second side (32) coupled to the growth substrate, the growth substrate thereby forming a temporary support surface; and substituting the temporary support surface with a permanent substrate (42 and 48) having at least one of a higher electrical conductivity and an increased optical transparency relative to the growth substrate, the substituting including wafer bonding the permanent substrate to one of the first and second sides of the LED layers, the wafer bonding including elevating the temperature at the interface of the permanent substrate and the LED layers to achieve a low resistance connection therebetween.
Claim 9
Dependent Claim
40 words
The method of claim 8 wherein substituting the temporary support surface includes removing the growth substrate (30) following the wafer bonding of the permanent substrate (48) to the first side (38) of the LED layers (32, 34, 36 and 38).
Claim 10
Dependent Claim
41 words
The method of claim 8 wherein substituting the temporary support surface includes removing the growth substrate (30) prior to the wafer bonding of the permanent substrate (42) to the second (32) side of the LED layers (32, 34, 36 and 38).
Claim 11
Dependent Claim
49 words
The method of claim 8, 9 or 10 further comprising wafer bonding a second electrically conductive, optically transparent substrate (48) on the LED layers (32, 34, 36 and 38), the permanent substrate being electrically conductive and optically transparent, thereby sandwiching the LED layers between transparent substrates (42 and 48).
Claim 12
Dependent Claim
35 words
The method of claim 8 further comprising flowing a dopant gas during the wafer bonding of the permanent substrate (42 and 48) so as to increase carrier concentration at the interface of the wafer bond.
Claim 13
Dependent Claim
82 words
The method of claim 8 further comprising applying a cap material to at least one of the permanent substrate (42) and the LED layers (32, 34, 36 and 38) to retard oxidation prior to the step of substituting the temporary support surface (30) with the permanent substrate (42 and 48), the method further comprising applying heat to decap the at least one of the permanent substrate and the LED layers for the wafer bonding of the permanent substrate to the LED layers.
Claim 14
Independent Claim
63 words
A method of stacking light emitting diodes (LEDs) comprising: epitaxially growing first LED layers (34, 36 and 38) to form a first LED structure (40); epitaxially growing second LED layers (66, 68 and 70) to form a second LED structure (64); stacking the first LED structure onto the second LED structure; and wafer bonding the first LED structure to the second LED structure.
Claim 15
Dependent Claim
31 words
The method of claim 14 wherein said first LED layers (34, 36 and 38) are grown on a temporary growth substrate (30), the method further comprising removing the temporary growth substrate.
Claim 16
Dependent Claim
31 words
The method of claim 14 wherein wafer bonding includes aligning the first and second LED structures (40 and 64) such that said first and second LED structures have the same polarity.
Claim 17
Dependent Claim
36 words
The method of claim 14 further comprising forming a tunnel junction (72) between the first and second LED structures (40 and 64), the tunnel junction having a polarity opposite to the first and second LED structures.
Claim 18
Independent Claim
81 words
A method of forming a light emitting diode (LED) having a plurality of layers including adjacent first and second layers (126 and 130) joined at an interface, the method comprising the steps of: patterning a first surface (138) of the first layer (126) such that at least one of the optical and electrical properties will selectively vary along the interface of the first and second layers (130); and wafer bonding the first surface of the first layer to the second layer.
Claim 19
Dependent Claim
42 words
The method of claim 18 further comprising epitaxially growing LED layers (130, 132 and 134), patterning the first surface (138) of the first layer (126) including selecting a pattern to define a desired electrical current path to the epitaxially grown LED layers.
Claim 20
Dependent Claim
32 words
The method of claim 18 wherein patterning the first surface (138) of the first layer (126) includes removing material from the first layer to form a depression (140) along the first surface.
Claim 21
Dependent Claim
38 words
The method of claim 20 further comprising forming an electrode (142) aligned with the depression (140) for applying a voltage, the electrode being positioned at a side of the first layer (126) opposite to the second layer (130).
Claim 22
Dependent Claim
22 words
The method of claim 18 wherein the first layer (126) is selected of a material to form a current spreading window layer.
Claim 23
Dependent Claim
28 words
The method of claim 18 wherein patterning the first surface (138) includes selecting a pattern to define a light reflection pattern for light generated by the LED (128).
Claim 24
Independent Claim
52 words
A method of forming a light emitting diode (LED) comprising: providing a first substrate (30); providing a II-VI LED structure (40) on the first substrate; and wafer bonding one of a III-V semiconductor substrate and a SiC substrate (48) to the II-VI LED structure, thereby enhancing stability of the II-VI LED structure.
References Cited (Backward Citations)
EP0420691A2
Cited
EP0434233A1
Cited
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