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`US 20040217360Al
`
`(19) United States
`(12) Patent Application Publication
`Negley
`
`(10) Pub. No.: US 2004/0217360 Al
`Nov. 4, 2004
`( 43) Pub. Date:
`
`(54) LIGHT-EMITTING DEVICES HAVING
`COPlANAR ELECTRICAL CONTACTS
`ADJACENT TO A SUBSTRATE SURFACE
`OPPOSITE AN ACTIVE REGION AND
`METHODS OF FORMING THE SAME
`
`(76)
`
`Inventor: Gerald H. Negley, Carrboro, NC (US)
`
`Correspondence Address:
`MYERS BIGEL SIBLEY & SAJOVEC
`PO BOX 37428
`RALEIGH, NC 27627 (US)
`
`(21) Appl. No.:
`
`I0/818,592
`
`(22) Filed:
`
`Apr. 6, 2004
`
`Related U.S. Application Data
`
`( 60) Provisional application No. 60/466,635, filed on Apr.
`30, 2003.
`
`Publication Classification
`
`Int. CI.7
`..................................................... HOIL 27/15
`(51)
`(52) U.S. CI. ................................................................ 257/79
`
`(57)
`
`ABSTRACT
`
`A light -emitting device includes a substrate having first and
`second opposing surfaces. An active region is on the first
`surface and first and second electrical contacts are adjacent
`to the second surface and are conductively coupled to the
`active region. In other embodiments, a light-emitting device
`includes a substrate having first and second opposing Sur(cid:173)
`faces. An active region is on the first surface and includes a
`first active layer having a first conductivity type on the first
`surface and a second active layer having a second conduc(cid:173)
`tivity type on the first active layer. A first electrical contact
`is adjacent to the second surface. A contact plug extends
`through the substrate and the active region and couples the
`first electrical contact to the second active layer. A second
`electrical contact is coupled to the substrate at the second
`surface.
`
`235
`
`220
`
`210a
`210b
`
`240b
`
`EVERLIGHT ELECTRONICS CO., LTD.
`Exhibit 1009
`
`

`

`Patent Application Publication Nov. 4, 2004 Sheet 1 of 5
`
`US 2004/0217360 A1
`
`100
`
`I
`
`130
`
`110b
`110a
`\
`
`I
`
`135
`120
`
`1
`
`115
`
`Substrate
`105
`
`FIG. 1
`(PRIOR ART)
`
`EVERLIGHT ELECTRONICS CO., LTD.
`Exhibit 1009
`
`

`

`Patent Application Publication Nov. 4, 2004 Sheet 2 of 5
`
`US 2004/0217360 Al
`
`220
`
`I 220
`
`I / 220
`
`235
`
`, ; 220
`
`Substrate
`205
`
`FIG. 2A
`
`225
`
`Substrate
`205
`
`FIG. 28
`
`230
`225
`
`Substrate
`205
`
`FIG. 2C
`
`230
`225
`
`Substrate
`205
`
`FIG. 20
`
`t
`210a
`210b
`\
`
`t
`210a
`210b
`\
`
`t
`210a
`210b
`\
`
`EVERLIGHT ELECTRONICS CO., LTD.
`Exhibit 1009
`
`

`

`Patent Application Publication Nov. 4, 2004 Sheet 3 of 5
`
`US 2004/0217360 Al
`
`f
`210b
`210a
`\
`
`II 220
`
`l r 235
`
`225
`230
`
`FIG. 2E
`
`220
`
`235
`
`220
`
`235
`
`FIG. 2F
`
`FIG. 2G
`
`EVERLIGHT ELECTRONICS CO., LTD.
`Exhibit 1009
`
`

`

`Patent Application Publication Nov. 4, 2004 Sheet 4 of 5
`
`US 2004/0217360 Al
`
`220
`
`235
`
`220
`
`235
`
`220
`
`235
`
`FIG. 2H
`
`FIG. 21
`
`FIG. 2J
`
`EVERLIGHT ELECTRONICS CO., LTD.
`Exhibit 1009
`
`

`

`Patent Application Publication Nov. 4, 2004 Sheet 5 of 5
`
`US 2004/0217360 Al
`
`235
`
`210a
`210b
`
`240b
`
`FIG. 2K
`
`EVERLIGHT ELECTRONICS CO., LTD.
`Exhibit 1009
`
`

`

`US 2004/0217360 A1
`
`Nov. 4, 2004
`
`1
`
`LIGHT-EMITTING DEVICES HAVING COPLANAR
`ELECTRICAL CONTACTS ADJACENT TO A
`SUBSTRATE SURFACE OPPOSITE AN ACTIVE
`REGION AND METHODS OF FORMING THE
`SAME
`
`RELATED APPLICATION
`
`[0001] This application claims the benefit of and priority
`to U.S. Provisional Patent Application No. 60/466,635, filed
`Apr. 30, 2003, the disclosure of which is hereby incorpo(cid:173)
`rated herein by reference as if set forth in its entirety.
`
`BACKGROUND OF THE INVENTION
`
`[0002] The present invention relates generally to micro(cid:173)
`electronic devices and fabrication methods therefor, and,
`more particularly, to light-emitting devices and fabrication
`methods therefor.
`
`[0003] Light-emitting diodes (LEDs) are widely used in
`consumer and commercial applications. As is well known to
`those skilled in the art, a light-emitting diode generally
`includes a diode region on a microelectronic substrate. The
`microelectronic substrate may comprise, for example, gal(cid:173)
`lium arsenide, gallium phosphide, alloys thereof, silicon
`carbide, and/or sapphire. Continued developments in LEDs
`have resulted in highly efficient and mechanically robust
`light sources that can cover the visible spectrum and beyond.
`These attributes, coupled with the potentially long service
`life of solid state devices, may enable a variety of new
`display applications, and may place LEDs in a position to
`compete with well entrenched incandescent and fluorescent
`lamps.
`
`[0004] Referring now to FIG. 1, a conventional GaN(cid:173)
`based LED 100 comprises a substrate 105, such as sapphire
`(A120 3) or SiC, that has first and second opposing surfaces
`110a and lOb, respectively, and may be at least partially
`transparent to optical radiation. A diode region, comprising
`ann-type layer 115 and a p-type layer 120 is disposed on the
`second surface 110b and is configured to emit optical
`radiation upon application of a voltage across the diode
`region, for example aeross ohmic contacts 130 and 135.
`[0005] The diode region including the n-type layer 115
`and/or the p-type layer 125 may comprise gallium nitride(cid:173)
`based semiconductor layers, including alloys thereof, such
`as indium gallium nitride and/or aluminum indium gallium
`nitride. The fabrication of gallium nitride on SiC is known
`to those skilled in the art, and is described, for example, in
`U.S. Pat. No. 6,177,688, the disclosure of which is hereby
`incorporated herein by reference. It will also be understood
`that a buffer layer or layers comprising aluminum nitride, for
`example, may be provided between the n-type gallium
`nitride layer 115 and the substrate 105, as described in U.S.
`Pat. Nos. 5,393,993, 5,523,589, 6,177,688, and application
`Ser. No. 09/154,363 entitled Vertical Geometry InGaN Light
`Emitting Diode, the disclosures of which are hereby incor(cid:173)
`porated herein by reference. Then-type gallium nitride layer
`115 may comprise silicon-doped gallium nitride, while the
`p-type gallium nitride layer 120 may comprise magnesium(cid:173)
`doped gallium nitride.
`
`In some LEDs, the ohmic contact 135 for the
`[0006]
`p-type gallium nitride layer 120 comprises platinum, nickel
`and/or titanium/gold. In other LEDs, a reflective ohmic
`
`contact comprising, for example, aluminum and/or silver,
`may be used. The ohmic contact 130 to the n-type gallium
`nitride layer 115 may comprise aluminum and/or titanium.
`Other suitable materials that form ohmic contacts to p-type
`gallium nitride and n-type gallium nitride may be used for
`ohmic contacts 135 and 130, respectively.
`[0007] Examples of ohmic contacts to n-type gallium
`nitride layers and p-type gallium nitride layers are described,
`for example, in U.S. Pat. No. 5,767,581, the disclosure of
`which is hereby incorporated herein by reference.
`
`[0008] Unfortunately, LED devices that have coplanar
`electrical contacts on the active side (i.e., the diode region
`side) may use thicker diode regions than other vertical
`designed LEDs to reduce current crowding (i.e., forcing
`electrons to make sharp turns).
`
`SUMMARY OF THE INVENTION
`
`[0009] According to some embodiments of the present
`invention, a light-emitting device comprises a substrate
`having first and second Opposing surfaces. An active region
`is on the first surface and first and second electrical contacts
`are adjacent to the second surface and are conductively
`coupled to the active region. Advantageously, such configu(cid:173)
`rations may allow electrical contacts to be coplanar on a
`non-active side of a substrate, which may obviate the need
`to use relatively thick active regions to reduce current
`crowding when electrical contacts are made coplanar on a
`non-active side of the substrate. As a result, more active
`devices may be formed on a single wafer.
`
`[0010]
`In other embodiments of the present invention, a
`light-emitting device comprises a substrate having first and
`second opposing surfaces. An active region is on the first
`surface and comprises a first active layer having a first
`conductivity type on the first surface and a second active
`layer having a second conductivity type on the first active
`layer. A first electrical contact is adjacent to the second
`surface. A contact plug extends through the substrate and the
`active region and couples the first electrical contact to the
`second active layer. A second electrical contact is coupled to
`the substrate at the second surface.
`
`[0011]
`In still further embodiments, a dielectric spacer is
`disposed between the contact plug and the substrate and
`between the contact plug and the first active layer. The
`dielectric spacer may comprise a material, such as spin-on(cid:173)
`glass, a polyimide, silicon-dioxide, and/or silicon-nitride.
`
`[0012]
`In still further embodiments, an ohmic contact
`layer is on the second active layer and the contact plug
`extends through the second active layer to contact the ohmic
`contact layer. The ohmic contact layer may comprise at least
`one of the following materials: TiN, platinum, nickel/gold,
`nickel oxide/gold, nickel oxide/platinum, Ti, and titanium/
`gold. The ohmic contact layer may also have a thickness
`between about 10 A and about 100 A and may be at least
`partially transparent.
`
`[0013]
`In other embodiments, a buffer layer, which may
`comprise aluminum nitride, may be disposed between the
`active region and the substrate, such that the contact plug
`extends through the buffer layer.
`
`[0014]
`In further embodiments, the substrate comprises a
`conductive material, such as SiC, and the contact plug
`
`EVERLIGHT ELECTRONICS CO., LTD.
`Exhibit 1009
`
`

`

`US 2004/0217360 Al
`
`Nov. 4, 2004
`
`2
`
`comprises a conductive material, such as gold, silver, gold
`alloys, and/or silver alloys. The first electrical contact may
`comprise platinum, nickel, and/or titanium/gold. The second
`electrical contact may comprise aluminum and/or titanium.
`
`[0015] Although described above primarily with respect to
`apparatus aspects of the present invention, methods of
`forming light-emitting devices are also described herein.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`[0016] Other features of the present invention will be more
`readily understood from the following detailed description
`of specific embodiments thereof when read in conjunction
`with the accompanying drawings, in which:
`
`[0017] FIG. 1 is a cross-sectional diagram that illustrates
`a conventional GaN-based light-emitting diode (LED); and
`
`[0018] FIGS. 2A-2K are cross sectional diagrams that
`illustrate light-emitting devices and methods of forming
`same in accordance with various embodiments of the present
`invention.
`
`DETAILED DESCRIPTION OF PREFERRED
`EMBODIMENTS
`[0019] While the invention is susceptible to various modi(cid:173)
`fications and alternative forms, specific embodiments
`thereof are shown by way of example in the drawings and
`will herein be described in detail. It should be understood,
`however, that there is no intent to limit the invention to the
`particular forms disclosed, but on the contrary, the invention
`is to cover all modifications, equivalents, and alternatives
`falling within the spirit and scope of the invention as defined
`by the claims. Like numbers refer to like elements through(cid:173)
`out the description of the figures. In the figures, the dimen(cid:173)
`sions of layers and regions are exaggerated for clarity. Each
`embodiment described herein also includes its complemen(cid:173)
`tary conductivity type embodiment.
`
`It will be understood that when an element such as
`[0020]
`a layer, region or substrate is referred to as being "on"
`another element, it can be directly on the other element or
`intervening elements may also be present. It will be under(cid:173)
`stood that if part of an element, such as a surface, is referred
`to as "inner," it is farther from the outside of the device than
`other parts of the element. Furthermore, relative terms such
`as "beneath" or "overlies" may be used herein to describe a
`relationship of one layer or region to another layer or region
`relative to a substrate or base layer as illustrated in the
`figures. It will be understood that these terms are intended to
`encompass different orientations of the device in addition to
`the orientation depicted in the figures. Finally, the term
`"directly" means that there are no intervening elements. A5
`used herein, the term "and/or" includes any and all combi(cid:173)
`nations of one or more of the associated listed items.
`
`It will be understood that, although the terms first,
`[0021]
`second, etc. may be used herein to describe various ele(cid:173)
`ments, components, regions, layers and/or sections, these
`elements, components, regions,
`layers and/or sections
`should not be limited by these terms. These terms are only
`used to distinguish one element, component, region, layer or
`section from another region, layer or section. Thus, a first
`region, layer or section discussed below could be termed a
`second region, layer or section, and, similarly, a second
`without departing from the teachings of the present inven(cid:173)
`tion.
`
`[0022] Embodiments of the present invention will now be
`described, generally, with reference to GaN-based light(cid:173)
`emitting diodes (LEDs) on SiC-based substrates. The
`present invention, however, is not limited to such structures.
`Embodiments of the invention may use other substrates
`including combinations, such as an AlGainP diode on a GaP
`substrate, a GaN diode on a SiC substrate, an SiC diode on
`an SiC substrate, and/or a nitride-based diode on a gallium
`nitride, silicon carbide, aluminum nitride, zinc oxide and/or
`other substrate. Moreover, the present invention is not
`limited to the use of a diode region as an active region. Other
`types of active regions may also be used in accordance with
`some embodiments of the present invention.
`
`[0023] Examples of light-emitting devices that may be
`used in embodiments of the present invention include, but
`are not limited to, the devices described in the following
`U.S. Pat. Nos. 6,201,262, 6,187,606, 6,120,600, 5,912,477,
`5,739,554, 5,631,190, 5,604,135, 5,523,589, 5,416,342,
`5,393,993, 5,338,944, 5,210,051, 5,027,168, 5,027,168,
`4,966,862 and/or 4,918,497, the disclosures of which are
`incorporated herein by reference. Other suitable LEDs and/
`or lasers are described in U.S. patent application Ser. No.
`10/140,796, entitled "GROUP III NITRIDE BASED
`LIGHT EMITTING DIODE STRUC'IURES WITH A
`QUANTUM WELL AND SUPERLATTICE, GROUP III
`NITRIDE BASED QUANTUM WELL STRUC'IURES
`AND GROUP III NITRIDE BASED SUPERLATTICE
`STRUC'IURES", filed May 7, 2002, as well as U.S. patent
`application Ser. No. 10/057,821, filed Jan. 25, 2002 entitled
`"LIGHT EMITTING DIODES INCLUDING SUBSTRATE
`MODIFICATIONS FOR LIGHT EXTRACTION AND
`MANUFACTURING METHODS THEREFOR" the disclo(cid:173)
`sures of which are incorporated herein as if set forth fully.
`Furthermore, phosphor coated LEDs, such as
`those
`described in U.S. patent application Ser. No. 10/659,241
`entitled
`"PHOSPHOR-COATED LIGHT EMITTING
`DIODES INCLUDING TAPERED SIDEWALLS, AND
`FABRICATION METHODS THEREFOR," filed Sep. 9,
`2003, the disclosure of which is incorporated by reference
`herein as if set forth full, may also be suitable for use in
`embodiments of the present invention.
`
`[0024] The LEDs and/or lasers may be configured to
`operate in a "flip-chip" configuration such that light emis(cid:173)
`sion occurs through the substrate. In such embodiments, the
`substrate may be patterned so as to enhance light output of
`the devices as is described, for example, in U.S. patent
`application Ser. No. 10/057,821, filed Jan. 25, 2002 entitled
`"LIGHT EMITTING DIODES INCLUDING SUBSTRATE
`MODIFICATIONS FOR LIGHT EXTRACTION AND
`MANUFACTURING METHODS THEREFOR" the disclo(cid:173)
`sure of which is incorporated herein by reference as if set
`forth fully herein.
`
`[0025] Referring now to FIGS. 2A-2H, light-emitting
`devices and methods of forming same, in accordance with
`some embodiments of the present invention, will now be
`described. As shown in FIG. 2A, a substrate 205, such as,
`for example, a SiC substrate, is provided. The substrate 205
`has a first surface 210a and a second surface 210b and may
`be at least partially transparent to optical radiation. A buffer
`layer or layers 220 comprising, for example, aluminum
`nitride may be formed on the first surface 210a of the
`substrate 205 as described in the above-incorporated U.S.
`
`EVERLIGHT ELECTRONICS CO., LTD.
`Exhibit 1009
`
`

`

`US 2004/0217360 Al
`
`Nov. 4, 2004
`
`3
`
`Pat. Nos. 5,393,993, 5,523,589, 6,177,688, and application
`Ser. No. 09/154,363 entitled Vertical Geometry InGaN Light
`Emitting Diode.
`
`[0026] Referring now to FIGS. 2B and 2C, an active
`region, such as, for example, a diode region comprising an
`n-type layer 225 and a p-type layer 230 may be epitaxially
`grown on the buffer layer 220. The diode region, including
`the n-type layer 225 and/or the p-type layer 230 may
`comprise gallium nitride-based semiconductor
`layers,
`including alloys thereof, such as indium gallium nitride,
`aluminum gallium nitride, and/or aluminum indium gallium
`nitride. The fabrication of gallium nitride layers is described,
`for example, in the above-incorporated U.S. Pat. No. 6,177,
`688. The n-type gallium nitride layer 225 may comprise
`silicon-doped gallium nitride, while the p-type gallium
`nitride layer 230 may comprise magnesium-doped gallium
`nitride.
`
`[0027] Referring now to FIG. 2D, an ohmic contact layer
`235 may be formed on the p-type gallium nitride layer 230.
`In accordance with various embodiments of the present
`invention, the ohmic contact layer 235 may comprise TIN,
`platinum, nickel/gold, nickel oxide/gold, nickel oxide/plati(cid:173)
`num, Ti, titanium/gold and/or alloys thereof. The ohmic
`contact layer 235 may have a thickness between about 10 A
`and about 100 A and may be at least partially transparent to
`optical radiation in accordance with some embodiments of
`the present invention.
`
`[0028] Referring now to FIG. 2E, a via is formed through
`the substrate 205, the buffer layer 220, and the diode region
`225, 230. In some embodiments, the via may be formed by
`etching the substrate 205, the buffer layer 220, and the diode
`region 225, 230 using the ohmic contact layer 235 as an etch
`stop layer. Various etching techniques may be used in
`accordance with different embodiments of the present inven(cid:173)
`tion, including, but not limited to, wet etching, dry etching,
`and micro-machining.
`
`[0029] Referring now to FIGS. 2F-2H, exemplary opera(cid:173)
`tions for forming a dielectric spacer on sides of the via will
`now be described. As shown in FIG. 2F, the via is at least
`partially filled with a dielectric material 240. By using, for
`example, sol-gel technology, spin-on-glass, a polyimide
`material, silicon dioxide and/or silicon nitride the dielectric
`material240 may be formed in the via in the liquid state and
`later etched after curing to a solid. A mask 245 is formed on
`the second surface 210b of the substrate 205 and patterned
`so as to expose a portion of the dielectric material 240 as
`shown in FIG. 2G. Referring now to FIG. 2H, the dielectric
`material 240 is etched through the mask 245 so as to leave
`a dielectric spacer 240a and 240b on sides of the via. Various
`etching techniques may be used in accordance with different
`embodiments of the present invention, including, but not
`limited to, wet etching, dry etching, and micro-machining.
`
`[0030] Referring now to FIG. 2I, a contact plug 250 is
`formed in the via by, for example, plating the via with a
`conductive material, such as gold, silver, gold alloys, and/or
`silver alloys, in accordance with some embodiments of the
`present invention.
`
`[0031] Referring now to FIG. 2J, a first electrical contact
`255 is formed adjacent to the second surface 210b such that
`the contact plug 250 couples the first electrical contact 255
`to the p-type gallium nitride layer 230 via the ohmic contact
`
`layer 235. Advantageously, because the ohmic contact layer
`235 contacts the p-type gallium nitride layer 230 across a
`relatively broad surface area, improved current spreading
`may be provided. The first electrical contact 255 for the
`p-type gallium nitride layer 230 may comprise platinum,
`nickel, titanium/gold and/or alloys thereof. In other embodi(cid:173)
`ments, a reflective ohmic contact comprising, for example,
`alumilium and/or silver, may be used to implement the first
`electrical contact 255.
`
`[0032] As shown in FIG. 2J, one or more second electri(cid:173)
`cal contact(s) 260 are formed on the second surface 210b of
`the substrate 205. The second electrical contact(s) 260 for
`the n-type gallium nitride layer 225 may comprise alumi(cid:173)
`num, titanium and/or alloys thereof. Other suitable materials
`that form ohmic contact to n-type gallium nitride may be
`used for the second electrical contact(s) 260. Examples of
`ohmic contacts to n-type gallium nitride layers and p-type
`gallium nitride layers are described, for example, in the
`above-incorporated U.S. Pat. No. 5,767,581. FIG. 2K
`shows the structure of FIG. 2J inverted with the diode
`region on top of the substrate 205.
`
`[0033] Advantageously, light-emitting devices, according
`to some embodiments of the present invention, may allow
`electrical contacts to be coplanar on a non-active side of a
`substrate, which may obviate the need to use relatively thick
`diode regions to reduce current crowding when electrical
`contacts are made coplanar on the active side of the sub(cid:173)
`strate. A<> a result, more active devices may be formed on a
`single wafer.
`
`[0034] Embodiments of the invention have been described
`above in which a diode is shown as an example of an active
`region. It should be understood, however, that an active
`region may include, but is not limited to, quantum wells,
`heterojunctions, homojunctions, multiple layers, combina(cid:173)
`tions of the foregoing, or the like, in accordance with some
`embodiments of the present invention. For example, layers
`225 and 230 may be embodied as described in the above(cid:173)
`referenced patents and/or applications. Moreover, additional
`layers, such as lattice strain layers, may also be incorporated
`in light-emitting devices in accordance with further embodi(cid:173)
`ments of the present invention.
`
`In concluding the detailed description, it should be
`[0035]
`noted that many variations and modifications can be made to
`the prefen-ed embodiments without substantially departing
`from the principles of the present invention. All such varia(cid:173)
`tions and modifications are intended to be included herein
`within the scope of the present invention, as set forth in the
`following claims.
`1. A light-emitting device, comprising:
`a substrate having first and second opposing surfaces;
`an active region comprising a first active layer having a
`first conductivity type on the first surface and a second
`active layer having a second conductivity type on the
`first active layer;
`a first electrical contact adjacent to the second surface;
`a contact plug extending through the substrate and the
`active region that couples the first electrical contact to
`the second active layer; and
`a second electrical contact that is coupled to the substrate
`at the second surface.
`
`EVERLIGHT ELECTRONICS CO., LTD.
`Exhibit 1009
`
`

`

`US 2004/0217360 Al
`
`Nov. 4, 2004
`
`4
`
`2. The light-emitting device of claim 1, further compris(cid:173)
`ing:
`
`a dielectric spacer on sides of the contact plug that
`separate the contact plug from the substrate and the first
`active layer.
`3. The light-emitting device of claim 2, wherein the
`dielectric spacer comprises spin-on-glass, a polyimide, sili(cid:173)
`con dioxide and/or silicon nitride.
`4. The light-emitting device of claim 1, further compris(cid:173)
`ing:
`
`an ohmic contact layer on the second active layer, the
`contact plug extending through the second active layer
`to contact the ohmic contact layer.
`5. The light-emitting device of claim 4, wherein the ohmic
`contact layer comprises at least one of TiN, platinum,
`nickel/gold, nickel oxide/gold, nickel oxide/platinum, Ti,
`and titanium/gold.
`6. The light-emitting device of claim 5, wherein the ohmic
`contact layer has a thickness between about 10 A and about
`100 A.
`7. The light-emitting device of claim 4, wherein the ohmic
`contact layer is at least partially transparent.
`8. The light-emitting device of claim 1, further compris(cid:173)
`ing:
`
`a buffer layer between the active region and the substrate,
`the contact plug extending through the buffer layer.
`9. The light-emitting device of claim 8, wherein the buffer
`layer comprises aluminum nitride.
`10. The light-emitting device of claim 1, wherein the
`substrate comprises SiC.
`11. The light-emitting device of claim 1, wherein the
`contact plug comprises gold, siler, a gold alloy, and/or a
`silver alloy.
`12. The light-emitting device of claim 1, wherein the first
`conductivity type is n-type, and wherein the second electri(cid:173)
`cal contact comprises at least one of aluminum and titanium.
`13. The light-emitting device of claim 1, wherein the
`second conductivity type is p-type, and wherein the first
`electrical contact comprises at least one of platinum, nickel,
`and titanium/gold.
`14. The light-emitting device of claim 1, wherein the first
`active layer comprises GaN.
`15. The light-emitting device of claim 1, wherein the
`second active layer comprises GaN.
`16. A light-emitting device, comprising:
`
`a substrate having first and second opposing surfaces;
`
`an active region on the first surface;
`
`first and second electrical contacts adjacent to the second
`surface that are conductively coupled to the active
`region.
`17. The light-emitting device of claim 16, wherein the
`active region comprises:
`
`a first active layer having a first conductivity type on the
`first surface; and
`
`a second active layer having a second conductivity type
`on the first active layer.
`
`18. The light-emitting device of claim 17, further com(cid:173)
`prising:
`a contact plug extending through the substrate and the
`active region that couples the first electrical contact to
`the second active layer.
`19. The light-emitting device of claim 18, further com(cid:173)
`prising:
`a dielectric spacer on sides of the contact plug that
`separate the contact plug from the substrate and the first
`active layer.
`20. The light-emitting device of claim 19, wherein the
`dielectric spacer comprises spin-on-glass, a polyimide, sili(cid:173)
`con dioxide, and/or silicon nitride.
`21. The light-emitting device of claim 18, further com(cid:173)
`prising:
`an ohmic contact layer on the second active layer, the
`contact plug extending through the second active layer
`to contact the ohmic contact layer.
`22. The light-emitting device of claim 21, wherein the
`ohmic contact layer comprises at least one of TiN, platinum,
`nickel/gold, nickel oxide/gold, nickel oxide/platinum, Ti,
`and titanium/gold.
`23. The light-emitting device of claim 22, wherein the
`ohmic contact layer has a thickness between about 10 A and
`about 100 A.
`24. The light-emitting device of claim 21, wherein the
`ohmic contact layer is at least partially transparent.
`25. 'lbe light-emitting device of claim 18, further com(cid:173)
`prising:
`a buffer layer between the active region and the substrate,
`the contact plug extending through the buffer layer.
`26. The light-emitting device of claim 25, wherein the
`buffer layer comprises aluminum nitride.
`27. The light-emitting device of claim 18, wherein the
`contact plug comprises gold, silver, a gold alloy, and/or a
`silver alloy.
`28. The light-emitting device of claim 17, wherein the first
`conductivity type is n-type, and wherein the second electri(cid:173)
`cal contact comprises at least one of aluminum and titanium.
`29. The light-emitting device of claim 17, wherein the
`second conductivity type is p-type, and wherein the first
`electrical contact comprises at least one of platinum, nickel,
`and titanium/gold.
`30. The light-emitting device of claim 17, wherein the first
`active layer comprises GaN.
`31. The light-emitting device of claim 17, wherein the
`second active layer comprises GaN.
`32. The light-emitting device of claim 16, wherein the
`substrate comprises SiC.
`33. A method of forming a light-emitting device, com(cid:173)
`prising:
`forming a first active layer having a first conductivity type
`on a first surface a substrate having first and second
`opposing surfaces;
`forming a second active layer having a second conduc(cid:173)
`tivity type on the first active layer, the first and second
`active layers comprising an active region;
`forming a via through the substrate and the active region;
`forming a contact plug in the via;
`forming a first electrical contact adjacent to the second
`surface, the contact plug coupling the first electrical
`contact to the second active layer; and
`
`EVERLIGHT ELECTRONICS CO., LTD.
`Exhibit 1009
`
`

`

`US 2004/0217360 Al
`
`Nov. 4, 2004
`
`5
`
`forming a second electrical contact that is coupled to the
`substrate at the second surface.
`34. The method of claim 33, further comprising:
`
`forming a dielectric spacer on sides of the contact plug
`that separate the contact plug from the substrate and the
`first active layer.
`35. The method of claim 34, wherein forming the dielec(cid:173)
`tric spacer comprises:
`
`filling at least a portion of the via with a dielectric
`material;
`
`forming a mask on the second surface; and
`
`etching the dielectric material through the mask.
`36. The method of claim 33, further comprising:
`
`forming an ohmic contact layer on the second active layer,
`the contact plug extending through the second active
`layer to contact the ohmic contact layer.
`37. The method of claim 33, wherein forming the via
`comprises:
`
`etching the substrate using the ohmic contact layer as an
`etch stop.
`38. The method of claim 37, wherein etching the substrate
`is performed using at least one of the following etching
`techniques: wet etching, dry etching, and micro-machining.
`39. The method of claim 33, further comprising:
`
`forming a buffer layer between the active region and the
`substrate, the contact plug extending through the buffer
`layer.
`40. The method of claim 33, wherein forming the contact
`plug comprises:
`
`plating the via with gold, silver, a gold alloy, and/or a
`silver alloy.
`
`41. A method of forming a light-emitting device, com(cid:173)
`prising:
`
`forming an active region on a first surface of a substrate
`having first and second opposing surfaces;
`
`forming first and second electrical contacts adjacent to the
`second surface that are conductively coupled to the
`active region.
`42. The method of claim 41, wherein forming the active
`region comprises:
`
`forming a first active layer having a first conductivity type
`on the first surface; and
`
`forming a second active layer having a second conduc(cid:173)
`tivity type on the first active layer.
`43. The method of claim 42, further comprising:
`
`forming a contact plug extending through the substrate
`and the active region that couples the first electrical
`contact to the second active layer.
`44. The method of claim 43, further comprising:
`
`forming a dielectric spacer on sides of the contact plug
`that separate the contact plug from the substrate and the
`first active layer.
`45. The method of claim 43, further comprising:
`
`forming an ohmic contact layer on the second active layer,
`the contact plug extending through the second active
`layer to contact the ohmic contact layer.
`46. The method of claim 43, further comprising:
`
`forming a buffer layer between the active region and the
`substrate, the contact plug extending through the buffer
`layer.
`
`* * * * *
`
`EVERLIGHT ELECTRONICS CO., LTD.
`Exhibit 1009
`
`