WO2020065539A1 - Phosphor converter structures for thin film packages and method of manufacture - Google Patents
Phosphor converter structures for thin film packages and method of manufacture Download PDFInfo
- Publication number
- WO2020065539A1 WO2020065539A1 PCT/IB2019/058106 IB2019058106W WO2020065539A1 WO 2020065539 A1 WO2020065539 A1 WO 2020065539A1 IB 2019058106 W IB2019058106 W IB 2019058106W WO 2020065539 A1 WO2020065539 A1 WO 2020065539A1
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- WO
- WIPO (PCT)
- Prior art keywords
- wavelength converting
- led
- converting material
- luminescent
- light emitting
- Prior art date
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- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 title claims abstract description 32
- 238000000034 method Methods 0.000 title claims abstract description 22
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 9
- 239000010409 thin film Substances 0.000 title claims description 25
- 239000000463 material Substances 0.000 claims abstract description 90
- 239000002245 particle Substances 0.000 claims abstract description 42
- 239000011230 binding agent Substances 0.000 claims abstract description 12
- 239000011159 matrix material Substances 0.000 claims abstract description 8
- 239000004065 semiconductor Substances 0.000 claims description 33
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 8
- 239000000853 adhesive Substances 0.000 claims description 6
- 230000001070 adhesive effect Effects 0.000 claims description 6
- 229920001296 polysiloxane Polymers 0.000 claims description 4
- 239000011248 coating agent Substances 0.000 claims description 3
- 238000000576 coating method Methods 0.000 claims description 3
- 238000010438 heat treatment Methods 0.000 claims description 2
- 238000000926 separation method Methods 0.000 claims description 2
- 239000000377 silicon dioxide Substances 0.000 claims 2
- 239000011575 calcium Substances 0.000 description 21
- 238000010586 diagram Methods 0.000 description 16
- MGVUQZZTJGLWJV-UHFFFAOYSA-N europium(2+) Chemical compound [Eu+2] MGVUQZZTJGLWJV-UHFFFAOYSA-N 0.000 description 16
- 239000007787 solid Substances 0.000 description 14
- 229910052791 calcium Inorganic materials 0.000 description 13
- 150000001875 compounds Chemical class 0.000 description 13
- 238000000465 moulding Methods 0.000 description 13
- 229910052712 strontium Inorganic materials 0.000 description 12
- 239000011777 magnesium Substances 0.000 description 10
- 229910052751 metal Inorganic materials 0.000 description 10
- 239000002184 metal Substances 0.000 description 10
- 229910052788 barium Inorganic materials 0.000 description 8
- -1 Ta02 Inorganic materials 0.000 description 6
- 229910052693 Europium Inorganic materials 0.000 description 5
- 229910052782 aluminium Inorganic materials 0.000 description 5
- JNDMLEXHDPKVFC-UHFFFAOYSA-N aluminum;oxygen(2-);yttrium(3+) Chemical compound [O-2].[O-2].[O-2].[Al+3].[Y+3] JNDMLEXHDPKVFC-UHFFFAOYSA-N 0.000 description 5
- OGPBJKLSAFTDLK-UHFFFAOYSA-N europium atom Chemical compound [Eu] OGPBJKLSAFTDLK-UHFFFAOYSA-N 0.000 description 5
- 229910052749 magnesium Inorganic materials 0.000 description 5
- 239000000203 mixture Substances 0.000 description 5
- 230000003287 optical effect Effects 0.000 description 5
- 229910019901 yttrium aluminum garnet Inorganic materials 0.000 description 5
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 4
- XXCMBPUMZXRBTN-UHFFFAOYSA-N strontium sulfide Chemical compound [Sr]=S XXCMBPUMZXRBTN-UHFFFAOYSA-N 0.000 description 4
- 239000011701 zinc Substances 0.000 description 4
- 229910020776 SixNy Inorganic materials 0.000 description 3
- 230000006835 compression Effects 0.000 description 3
- 238000007906 compression Methods 0.000 description 3
- 239000003989 dielectric material Substances 0.000 description 3
- 229910052732 germanium Inorganic materials 0.000 description 3
- 229910052909 inorganic silicate Inorganic materials 0.000 description 3
- 239000011572 manganese Substances 0.000 description 3
- 229910052710 silicon Inorganic materials 0.000 description 3
- 239000000758 substrate Substances 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 description 2
- 239000000956 alloy Substances 0.000 description 2
- 229910045601 alloy Inorganic materials 0.000 description 2
- 238000003491 array Methods 0.000 description 2
- 229910052796 boron Inorganic materials 0.000 description 2
- JGIATAMCQXIDNZ-UHFFFAOYSA-N calcium sulfide Chemical compound [Ca]=S JGIATAMCQXIDNZ-UHFFFAOYSA-N 0.000 description 2
- 239000002019 doping agent Substances 0.000 description 2
- 229910052733 gallium Inorganic materials 0.000 description 2
- 229910052738 indium Inorganic materials 0.000 description 2
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 2
- 229910052700 potassium Inorganic materials 0.000 description 2
- 229910052761 rare earth metal Inorganic materials 0.000 description 2
- 150000002910 rare earth metals Chemical class 0.000 description 2
- 229910052701 rubidium Inorganic materials 0.000 description 2
- 229910052709 silver Inorganic materials 0.000 description 2
- 239000004332 silver Substances 0.000 description 2
- 229910052708 sodium Inorganic materials 0.000 description 2
- 229910000679 solder Inorganic materials 0.000 description 2
- 229910052725 zinc Inorganic materials 0.000 description 2
- 229910017107 AlOx Inorganic materials 0.000 description 1
- 229910017115 AlSb Inorganic materials 0.000 description 1
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 description 1
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 1
- 239000005132 Calcium sulfide based phosphorescent agent Substances 0.000 description 1
- 229910004613 CdTe Inorganic materials 0.000 description 1
- 229910052684 Cerium Inorganic materials 0.000 description 1
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 1
- 229910002601 GaN Inorganic materials 0.000 description 1
- 229910005540 GaP Inorganic materials 0.000 description 1
- 229910005542 GaSb Inorganic materials 0.000 description 1
- GYHNNYVSQQEPJS-UHFFFAOYSA-N Gallium Chemical compound [Ga] GYHNNYVSQQEPJS-UHFFFAOYSA-N 0.000 description 1
- 229910001218 Gallium arsenide Inorganic materials 0.000 description 1
- 229910000673 Indium arsenide Inorganic materials 0.000 description 1
- GPXJNWSHGFTCBW-UHFFFAOYSA-N Indium phosphide Chemical compound [In]#P GPXJNWSHGFTCBW-UHFFFAOYSA-N 0.000 description 1
- 229910015811 MSi2 Inorganic materials 0.000 description 1
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 1
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 1
- 229910017623 MgSi2 Inorganic materials 0.000 description 1
- 229910052777 Praseodymium Inorganic materials 0.000 description 1
- KJTLSVCANCCWHF-UHFFFAOYSA-N Ruthenium Chemical compound [Ru] KJTLSVCANCCWHF-UHFFFAOYSA-N 0.000 description 1
- 229910052772 Samarium Inorganic materials 0.000 description 1
- 229910004074 SiF6 Inorganic materials 0.000 description 1
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 1
- 239000012190 activator Substances 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- DSAJWYNOEDNPEQ-UHFFFAOYSA-N barium atom Chemical compound [Ba] DSAJWYNOEDNPEQ-UHFFFAOYSA-N 0.000 description 1
- 230000004888 barrier function Effects 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- UHYPYGJEEGLRJD-UHFFFAOYSA-N cadmium(2+);selenium(2-) Chemical compound [Se-2].[Cd+2] UHYPYGJEEGLRJD-UHFFFAOYSA-N 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- ZMIGMASIKSOYAM-UHFFFAOYSA-N cerium Chemical compound [Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce] ZMIGMASIKSOYAM-UHFFFAOYSA-N 0.000 description 1
- XQTIWNLDFPPCIU-UHFFFAOYSA-N cerium(3+) Chemical compound [Ce+3] XQTIWNLDFPPCIU-UHFFFAOYSA-N 0.000 description 1
- 229910019990 cerium-doped yttrium aluminum garnet Inorganic materials 0.000 description 1
- 229910052804 chromium Inorganic materials 0.000 description 1
- 239000011651 chromium Substances 0.000 description 1
- 239000003086 colorant Substances 0.000 description 1
- 239000004020 conductor Substances 0.000 description 1
- 239000002178 crystalline material Substances 0.000 description 1
- 238000006073 displacement reaction Methods 0.000 description 1
- 239000010408 film Substances 0.000 description 1
- 239000002223 garnet Substances 0.000 description 1
- GNPVGFCGXDBREM-UHFFFAOYSA-N germanium atom Chemical compound [Ge] GNPVGFCGXDBREM-UHFFFAOYSA-N 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 1
- 229910052737 gold Inorganic materials 0.000 description 1
- 239000010931 gold Substances 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 238000005286 illumination Methods 0.000 description 1
- WPYVAWXEWQSOGY-UHFFFAOYSA-N indium antimonide Chemical compound [Sb]#[In] WPYVAWXEWQSOGY-UHFFFAOYSA-N 0.000 description 1
- RPQDHPTXJYYUPQ-UHFFFAOYSA-N indium arsenide Chemical compound [In]#[As] RPQDHPTXJYYUPQ-UHFFFAOYSA-N 0.000 description 1
- APFVFJFRJDLVQX-UHFFFAOYSA-N indium atom Chemical compound [In] APFVFJFRJDLVQX-UHFFFAOYSA-N 0.000 description 1
- AMGQUBHHOARCQH-UHFFFAOYSA-N indium;oxotin Chemical compound [In].[Sn]=O AMGQUBHHOARCQH-UHFFFAOYSA-N 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 229910052748 manganese Inorganic materials 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 229910003465 moissanite Inorganic materials 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 150000004767 nitrides Chemical class 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 230000006911 nucleation Effects 0.000 description 1
- 238000010899 nucleation Methods 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 229910052763 palladium Inorganic materials 0.000 description 1
- 229910052697 platinum Inorganic materials 0.000 description 1
- 229920003223 poly(pyromellitimide-1,4-diphenyl ether) Polymers 0.000 description 1
- PUDIUYLPXJFUGB-UHFFFAOYSA-N praseodymium atom Chemical compound [Pr] PUDIUYLPXJFUGB-UHFFFAOYSA-N 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 229910052702 rhenium Inorganic materials 0.000 description 1
- WUAPFZMCVAUBPE-UHFFFAOYSA-N rhenium atom Chemical compound [Re] WUAPFZMCVAUBPE-UHFFFAOYSA-N 0.000 description 1
- 229910052703 rhodium Inorganic materials 0.000 description 1
- 239000010948 rhodium Substances 0.000 description 1
- MHOVAHRLVXNVSD-UHFFFAOYSA-N rhodium atom Chemical compound [Rh] MHOVAHRLVXNVSD-UHFFFAOYSA-N 0.000 description 1
- 229910052707 ruthenium Inorganic materials 0.000 description 1
- KZUNJOHGWZRPMI-UHFFFAOYSA-N samarium atom Chemical compound [Sm] KZUNJOHGWZRPMI-UHFFFAOYSA-N 0.000 description 1
- SBIBMFFZSBJNJF-UHFFFAOYSA-N selenium;zinc Chemical compound [Se]=[Zn] SBIBMFFZSBJNJF-UHFFFAOYSA-N 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 229910010271 silicon carbide Inorganic materials 0.000 description 1
- 229910052814 silicon oxide Inorganic materials 0.000 description 1
- 238000001228 spectrum Methods 0.000 description 1
- CIOAGBVUUVVLOB-UHFFFAOYSA-N strontium atom Chemical compound [Sr] CIOAGBVUUVVLOB-UHFFFAOYSA-N 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 230000000153 supplemental effect Effects 0.000 description 1
- 229910052719 titanium Inorganic materials 0.000 description 1
- 239000010936 titanium Substances 0.000 description 1
- 229910052723 transition metal Inorganic materials 0.000 description 1
- 150000003624 transition metals Chemical class 0.000 description 1
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 1
- 229910052721 tungsten Inorganic materials 0.000 description 1
- 239000010937 tungsten Substances 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L33/48—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor body packages
- H01L33/50—Wavelength conversion elements
- H01L33/505—Wavelength conversion elements characterised by the shape, e.g. plate or foil
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L2933/00—Details relating to devices covered by the group H01L33/00 but not provided for in its subgroups
- H01L2933/0008—Processes
- H01L2933/0033—Processes relating to semiconductor body packages
- H01L2933/0041—Processes relating to semiconductor body packages relating to wavelength conversion elements
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L33/44—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the coatings, e.g. passivation layer or anti-reflective coating
- H01L33/46—Reflective coating, e.g. dielectric Bragg reflector
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L33/48—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor body packages
- H01L33/50—Wavelength conversion elements
- H01L33/501—Wavelength conversion elements characterised by the materials, e.g. binder
Definitions
- Semiconductor light-emitting devices or optical power emitting devices such as devices that emit ultraviolet (UV) or infrared (JR) optical power
- LEDs semiconductor light or optical power emitting devices
- LEDs are attractive candidates for light sources, such as camera flashes, for hand-held battery-powered devices, such as cameras and cell phones.
- a single LED may provide light that is less bright than a typical light source, and, therefore, arrays of LEDs may be used for such applications.
- a method includes providing a layer of a wavelength converting material on a temporary tape.
- the wavelength converting material includes at least a binder or matrix material, particles of a non-luminescent material, and phosphor particles and has a concentration of 60% - 90% by volume particles of the non-luminescent material and phosphor particles.
- the layer of the wavelength converting material is separated on the temporary tape to form multiple wavelength converting structures, which are provided on an array type frame. Heat and pressure are apphed to the wavelength converting structures on the array type frame.
- FIG. 1 is a flow diagram of an example method of manufacturing a light emitting device (LED);
- FIGs. 2A, 2B, 2C, 2D, 2E, 2F and 2G are diagrams of the example LED at various stages during the manufacturing process
- FIG. 3A is a diagram of an example LED die
- FIG. 3B is a diagram of an example light emitting semiconductor structure that may be included in the LED die of FIG. 3A.
- FIG. 3C is a diagram of an example LED that may include the LED die of FIG. 3A.
- LEDs light emitting devices
- Such LEDs may be referred to as white LEDs.
- White LEDs may appear to emit white light from the perspective of the viewer when the LEDs are in an on state. However, they may actually be made up of light emitting semiconductor structures that emit non-white pump light (e.g., blue or UV hght) as well as wavelength converting structures that make the non white pump hght appear white to the viewer.
- non-white pump light e.g., blue or UV hght
- reflectors may sometimes be disposed adjacent the side edges of each LED to prevent hght from escaping the LED through the sides.
- these reflectors are thick (e.g., over 25 microns thick) to prevent the pump light from seeping through.
- a non-metallic, thin film reflector such as a Bragg reflector, which may be much thinner (e.g., 1-10 microns thick).
- Use of non-metallic, thin film reflectors may be desirable in applications such as where close placement of LEDs is required.
- Non-metallic, thin film reflectors are typically made from materials, such as AlOx, Ti02, Ta02, Si02, Nb205, etc., which have low coefficients of thermal expansion (“CTE”s ⁇ 6-20ppm) in comparison to materials, such as phosphor in glass or ceramic phosphor, that conventionally form the wavelength converting structures. If a non-metalhc, thin film reflector is coated on side surfaces of an LED that includes a light emitting semiconductor structure and a wavelength converting structure, the non-metalhc, thin film reflector may crack due to CTE mismatch between the non-metalhc, thin film reflector and the wavelength converting structure.
- wavelength converting structures may be formed from a wavelength converting material that is highly loaded and has a better CTE match with non-metalhc, thin film reflector materials than the conventional wavelength converting materials described above.
- Such highly loaded wavelength converting material may be a molding compound formed from a binder or matrix material, such as silicone, that is highly loaded with phosphor particles as well as solid particles of a non-luminescent material, such as sihca (Si0 2 i n amorphous or crystalline form).
- a concentration of solids (the phosphor and sohd, non-luminescent particles) in the molding compound may be 60% - 90% by volume.
- Embodiments described herein provide methods whereby a highly loaded wavelength converting structure, such as described above, may be manufactured to have sufficiently smooth side surfaces (e.g., 100 nm roughness or less). While embodiments are described herein with respect to a highly loaded wavelength converting material, one of ordinary skill in the art will recognize that the methods described herein may be used with any type of wavelength converting structure where surface smoothness is desirable.
- FIG. 1 is a flow diagram 100 of an example method of manufacturing an LED.
- FIGs. 2A, 2B, 2C, 2D, 2E, 2F and 2G are diagrams of the example LED at various stages during the manufacturing process.
- a layer of wavelength converting material is provided on a temporary tape (102).
- the wavelength converting material may be a molding compound formed from a binder or matrix material, such as silicone, that is highly loaded with phosphor particles as well as solid particles of a non-luminescent material, such as sihca (S1O2).
- a concentration of solids (the phosphor and non-luminescent particles) in the molding compound may be between 60 and 90% by volume. In one embodiment, the concentration of sohds (the phosphor and non-luminescent particles) in the molding compound is greater than 70% by volume. In another embodiment, the concentration of solids in the molding compound is greater than 80% by volume.
- FIG. 2A is a diagram of an example 200A of a layer of a wavelength converting material 204 disposed on a temporary tape 202.
- the wavelength converting material may be formed for use with a semiconductor structure that emits blue light.
- the wavelength converting material may include, for example, particles of a yellow emitting wavelength converting material or green and red emitting wavelength converting materials, which will produce white light when the light emitted by the respective phosphors combines with the blue hght emitted by the light emitting semiconductor structure.
- the wavelength converting material may be formed for use with a semiconductor structure that emits UV light.
- the wavelength converting material may include, for example, particles of blue and yellow wavelength converting materials or particles of blue, green and red wavelength converting materials. Wavelength converting particles emitting other colors of light may be added to tailor the spectrum of light emitted from the LED.
- the luminescent, solid particles in the wavelength converting material may be composed of U 3 A1 d O ⁇ 2 :Ob 3+ .
- the luminescent, sohd particles may be an amber to red emitting rare earth metal-activated oxonitridoalumosilicate of the general formula (Cai. x.y.z Sr x Ba y Mg z )i. n (Ali. a+b Ba)Sii- b N3- b O b :RE n wherein 0 ⁇ x ⁇ l, 0 ⁇ y ⁇ l, 0 ⁇ z ⁇ l, 0 ⁇ a ⁇ l, 0 ⁇ b ⁇ l and
- RE may be selected from europium(II) and cerium(III).
- the luminescent, sohd particles in the wavelength converting material may include aluminum garnet phosphors with the general formula (Lui. x.y.a.b Y x Gd y )3(Ali. z Ga z )50i2: Ce a Prb, wherein 0 ⁇ x ⁇ l, 0 ⁇ y ⁇ l, 0 ⁇ z ⁇ 0.1, 0 ⁇ a ⁇ 0.2 and 0 ⁇ b ⁇ 0.1, such as Lu3Al50i2:Ce 3+ and U3A1 d O ⁇ 2:Ob 3+ , which emits light in the yellow-green range; and (Sri.
- Suitable phosphors include, CaAlSiN3:Eu 2+ ,(Sr,Ca)AlSiN3:Eu 2+ , and (Sr, Ca, Mg, Ba, Zn)(Al, B, In, Ga)(Si, Ge)N 3 :Eu 2+ .
- the luminescent, sohd particles in the wavelength converting material may also have a general formula (Sri. a. b Ca b Ba c Mg d Zn e )Si x N y O z :Eu a 2+ , wherein 0.002 ⁇ a ⁇ 0.2, 0.0 ⁇ b ⁇ 0.25, 0.0 ⁇ c ⁇ 0.25, 0.0 ⁇ d ⁇ 0.25, 0.0 ⁇ e ⁇ 0.25, 1.5 ⁇ x ⁇ 2.5, 1.5 ⁇ y ⁇ 2.5 andl.5 ⁇ z ⁇ 2.5.
- M is one or more elements selected from Mg (magnesium), Ca (calcium), Sr (strontium), Ba (barium) and Zn (zinc)
- the element A is one or more elements selected from B (boron), A1 (aluminum), In (indium) and Ga (gallium)
- the element B is Si (sihcon) and/or Ge (germanium)
- the element Z is one or more elements selected from rare earth or transition metals.
- the element Z is at least one or more elements selected from Eu (europium), Mg (manganese), Sm (samarium) and Ce (cerium).
- the element A can be A1 (aluminum)
- the element B can be Si (silicon)
- the element Z can be Eu (europium).
- the luminescent, solid particles in the wavelength converting material may also be a chemically-altered Ce: YAG (Yttrium Aluminum Garnet) phosphor that is produced by doping the Ce: YAG phosphor with the trivalent ion of praseodymium (Pr).
- the luminescent, solid particles in the wavelength converting material may include a main fluorescent material and a supplemental fluorescent material.
- the main fluorescent material may be a Ce: YAG phosphor and the supplementary fluorescent material may be europium (Eu) activated strontium sulfide (SrS) phosphor (“Eu:SrS”).
- the main fluorescence material may also be a Ce: YAG phosphor or any other suitable yellow-emitting phosphor
- the supplementary fluorescent material may also be a mixed ternary crystalline material of calcium sulfide (CaS) and strontium sulfide (SrS) activated with europium ((Ca x Sri x )S:Eu 2+ ).
- the main fluorescent material may also be a Ce:YAG phosphor or any other suitable yellow-emitting phosphor
- the supplementary fluorescent material may also be a nitrido-sihcate doped with europium.
- the nitrido-silicate supplementary fluorescent material may have the chemical formula (Sri.
- the wavelength converting material may include a blend of any of the above-described phosphors.
- Materials and concentrations of the non-luminescent, solid particles may be chosen at least in part based on the chosen phosphor or phosphors such that the molding compound has a CTE that matches or closely matches the CTE of a non-metallic, thin film reflector that is to be coated on side surfaces of the light emitting semiconductor structure and wavelength converting structure.
- the CTE of the molding compound can be around 20PPM if the loading is close to 90%.
- the refraction index of the inert material may be matched as close as possible to the refraction index of the binder.
- the refraction index of the binder may be 1.5
- the refraction index of the Si02 is 1.46.
- a binder with a refraction index of 1.41 may be used in combination with Si02.
- the volume % may calculated by taking into account of the mass of each of the solid components plus the mass of the binder divided and the specific gravity of each component.
- FIG. 2B is a diagram of an example of the individual wavelength converting structures 204 disposed on the temporary tape 202 after sawing or separation. Both a side view 200B and a top view 200C of the tape 202 are provided in FIG. 2B. In the side view 200B, five wavelength converting structures 204A, 204B, 204C, 204D and 204E are shown provided on the temporary tape 202. In the top view 200C, nine wavelength converting structures are shown, including the wavelength converting structures 204A, 204B and 204C. While five and nine wavelength converting structures are illustrated in views 200B and 200C in FIG.
- the wavelength converting layer 204 may be separated into any number of wavelength converting structures on the temporary tape 202 within the scope of the embodiments described herein.
- side edges e.g., 250A, 250B, 250C and 250D as labeled for one of the wavelength converting structures in top view 200C of FIG. 2B
- FIGs. 2C and 2D are diagrams 200D and 200E showing the wavelength converting structures 204A, 204B and 204C after transfer.
- the wavelength converting structures 204A, 204B and 204C are provided on a structure, which may be formed from a metal frame 210 that is adhered to another tape 206, such as a Kapton tape, via a thermal release tape or layer 208.
- the frame 210 includes raised regions that define recessed areas 260 in which respective wavelength converting structures are to be compressed. While not visible in the side view in FIG.
- the raised regions may form an array such that each individual wavelength converting structure is disposed in a respective recessed area 260 in the frame 210.
- a release film 214 may be stretched over the frame 210 and the individual wavelength converting structures 204A, 204B and 204C.
- the individual wavelength converting structures may be compression molded on the tape 206 and within the frame 210 (108).
- the structure, including the tape 206, the thermal release tape or layer 208, and the metal frame 210 may be placed within a diaphragm 216 and subjected to pressure and heat sufficient to cause the individual wavelength converting structures to flow within the respective recessed areas 260A, 260B and 260C.
- an effective pressure may be in a range of 0.7- 0.8Mpa and an effective heat may be in a range of 50-90°C.
- FIG. 2E is a diagram 200F of the wavelength converting structures after compression using the diaphragm 216.
- individual wavelength converting structures 218A, 218B and 218C take the shape of the respective recessed areas 260A, 260B and 260C in which they are disposed.
- the raised portions of the frame 210 may have smooth inner walls 213 such that the individual wavelength converting structures 218, after compression, will have smooth edges (e.g., 100 nm roughness or less) that are, for example, suitable for use with a thin film reflector such as a Bragg reflector (not shown).
- a respective light emitting die may be attached to each individual wavelength converting structure (110).
- the wavelength converting molding compound may have enough adhesion such that the hght emitting dies may be attached thereto without any additional adhesive.
- the dice may thus be attached using heat to the individual wavelength converting structures, such as by using the heated collet of a die attach machine.
- a wavelength converting structure would be attached to a die using some type of intervening adhesive material, which may cause wave guiding at the interface with the adhesive material.
- the wavelength converting structures formed using the above-mentioned materials and using the methods described above may have sufficient adhesion such that the intervening adhesive material is not needed, such light guiding may be eliminated, further reducing the potential for hght leakage through the sides of the LEDs and any thin film reflector coated thereon.
- FIG. 2F is a diagram 200G of individual LEDs 270A, 270B and 270C after attaching the light emitting dies 230A, 230B and 230C to their respective wavelength converting structures 218A, 218B and 218C and subsequent curing.
- the individual LEDs 270A, 270B and 270C may then be released from the frame 210, for example, by heating the thermal release tape or layer 208 (112).
- FIG. 2G is a diagram 200H showing LEDs 270A, 270B and 270C, attached to the tape 206, formed by the method 100.
- FIG. 3A is a diagram of an example LED die 230 that may be attached to a wavelength converting structure, as described above.
- the LED die 230 includes a hght emitting semiconductor structure 302.
- Contacts 304 and 306 may be coupled to the light emitting semiconductor structure 302, either directly or via another structure such as a submount, for electrical connection to a circuit board or other substrate or device.
- the contacts 304 and 306 may be electrically insulated from one another by a gap 308, which may be filled with a dielectric material.
- the light emitting semiconductor structure 302 may be any light emitting semiconductor structure that emits light that may be converted to light having a different color point via a wavelength converting material.
- the light emitting semiconductor structure 302 may be formed from III- V semiconductors including, but not limited to, AIN, A1P, ALAs, AlSb, GaN, GaP, GaAs, GaSb, InN, InP, InAs, InSb, II-VI semiconductors including, but not limited to, ZnS, ZnSe, CdSe, CdTe, group IV semiconductors including, but not limited to Ge, Si, SiC, and mixtures or alloys thereof.
- Ill-Nitride semiconductors such as GaN
- Ill-Phosphide semiconductors such as InGaP
- Contacts 304 and 306 may be formed from a solder, such as AuSn, AuGa, AuSi or SAC solders.
- FIG. 3B is a diagram of an example light emitting semiconductor structure 302 that may be included in the LED die 230 of FIG. 3A.
- the illustrated example is a flip chip structure.
- the embodiments described herein may be applied to other types of LED designs, such as vertical, lateral, and multi- junction devices.
- the light emitting semiconductor structure 302 includes a hght emitting active region 312 disposed between a semiconductor layer or region of n-type conductivity (also referred to as an n-type region) 310 and a semiconductor layer or region of p-type conductivity (also referred to as a p-type region) 314.
- Contacts 316 and 318 are disposed in contact with a surface of the light emitting semiconductor structure 302 and electrically insulated from one another by a gap 320, which may be filled by a dielectric material, such as an oxide or nitride of sihcon (i.e., S1O2 or S13N4).
- contact 316 (also referred to as a p-contact) is in direct contact with a surface of the p-type region 314, and the contact 318 (also referred to as an n-contact) is in direct contact with a surface of the n-type region 310.
- a dielectric material such as disposed in the gap 320, may also line side walls of the hght emitting active region 312 and p-type region 314 to electrically insulate those regions from the contact 318 to prevent shorting of the p-n junction.
- the n-type region 310 may be grown on a growth substrate and may include one or more layers of semiconductor material. Such layer or layers may include different compositions and dopant concentrations including, for example, preparation layers, such as buffer or nucleation layers, and/or layers designed to facilitate removal of the growth substrate. These layers may be n-type or not intentionally doped, or may even be p-type device layers. The layers may be designed for particular optical, material, or electrical properties desirable for the light emitting region to efficiently emit hght. Like the n-type region 310, the p- type region 314 may include multiple layers of different composition, thickness, and dopant concentrations, including layers that are not intentionally doped, or n-type layers.
- the light emitting active region 312 may be, for example, a p-n diode junction associated with the interface of p-region 314 and n-region 310.
- the light emitting active region 312 may include one or more semiconductor layers that are doped n-type or p-type or are un-doped.
- the light emitting active region 312 may include a single thick or thin light emitting layer. This includes a homojunction, single heterostructure, double heterostructure, or single quantum well structure.
- the light emitting active region 312 may be a multiple quantum well light emitting region, which may include multiple quantum well light emitting layers separated by barrier layers.
- the p-contact 316 may be formed on a surface of the p-type region
- the p-contact 316 may include multiple conductive layers, such as a reflective metal and a guard metal, which may prevent or reduce electromigration of the reflective metal.
- the reflective metal may be silver or any other suitable material, and the guard metal may be TiW or TiWN.
- the n- contact 318 may be formed in contact with a surface of the n-type region 310 in an area where portions of the active region 312, the n-type region 310, and the p- contact 316 have been removed to expose at least a portion of the surface of the n-type region 310.
- the sidewall of the exposed mesa or via may be coated with a dielectric to prevent shorting.
- the contacts 316 and 318 may be, for example, metal contacts formed from metals including, but not limited to, gold, silver, nickel, aluminum, titanium, chromium, platinum, palladium, rhodium, rhenium, ruthenium, tungsten, and mixtures or alloys thereof. In other examples, one or both contacts 316 and 318 may be formed from transparent conductors, such as indium tin oxide.
- the n-contact 318 and p-contact 316 are not limited to the arrangement illustrated in FIG. 3B and may be arranged in any number of different ways.
- one or more n-contact vias may be formed in the light emitting semiconductor structure 302 to make electrical contact between the n-contact 318 and the n-type layer 310.
- the n-contact 318 and p-contact 316 may be redistributed to form bond pads with a dielectric/metal stack as known in the art.
- the p-contact 316 and the n-contact 318 may be electrically connected to the contacts 304 and 306 of FIG. 3A, respectively, either directly or via another structure, such as a submount.
- FIG. 3C is a diagram of an example LED 330.
- the LED 330 includes an LED die 230.
- a wavelength converting structure 218 is disposed in direct contact with a surface 352 of the LED die 230.
- a thin film reflector 360 such as a Bragg reflector, may be a coating on side surfaces 370 of a structure formed from the LED die 230 and the wavelength converting structure 218 such that the thin film reflector 360 may be in direct contact with side surfaces of both the wavelength converting structure 218 and the LED die 230.
- the wavelength converting structure 218 having properties such as described above has sufficient CTE match with the thin film reflector 360 such that the thin film reflector 360 does not crack when in direct contact with the wavelength converting structure 218.
- the wavelength converting structure 218 may have a roughness of 100 nm or less, as described in detail above, which is sufficient for use with the thin film reflector 360 such that un-converted pump light and converted light do not leak through the side surfaces 370 and through the thin film reflector 360.
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Abstract
Light emitting devices (LEDs) and methods of manufacturing LEDs are described. A method includes providing a layer of a wavelength converting material on a temporary tape. The wavelength converting material includes at least a binder or matrix material, particles of a non-luminescent material, and phosphor particles and has a concentration of 60% - 90% by volume particles of the non-luminescent material and phosphor particles. The layer of the wavelength converting material is separated on the temporary tape to form multiple wavelength converting structures, which are placed in an array type frame. Heat and pressure are applied to the wavelength converting structures in the array type frame.
Description
PHOSPHOR CONVERTER STRUCTURES FOR THIN FILM PACKAGES
AND METHOD OF MANUFACTURE
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This apphcation claims benefit of priority to European Patent
Application No. 18205710.9 filed November 12, 2018 and to U.S. Patent
Application No. 16/142,247 filed September 26, 2018, each of which is
incorporated herein by reference in its entirety.
BACKGROUND
[0002] Semiconductor light-emitting devices or optical power emitting devices (such as devices that emit ultraviolet (UV) or infrared (JR) optical power), including light emitting diodes, resonant cavity light emitting diodes, vertical cavity laser diodes, and edge emitting lasers, are among the most efficient fight sources currently available. Due to their compact size and lower power requirements, for example, semiconductor light or optical power emitting devices (referred to herein as LEDs for simplicity) are attractive candidates for light sources, such as camera flashes, for hand-held battery-powered devices, such as cameras and cell phones. They may also be used, for example, for other applications, such as for automotive fighting, torch for video, and general illumination, such as home, shop, office and studio fighting, theater/stage lighting and architectural lighting. A single LED may provide light that is less bright than a typical light source, and, therefore, arrays of LEDs may be used for such applications.
SUMMARY
[0003] Light emitting devices (LEDs) and methods of manufacturing LEDs are described. A method includes providing a layer of a wavelength converting material on a temporary tape. The wavelength converting material includes at least a binder or matrix material, particles of a non-luminescent material, and phosphor particles and has a concentration of 60% - 90% by volume particles of
the non-luminescent material and phosphor particles. The layer of the wavelength converting material is separated on the temporary tape to form multiple wavelength converting structures, which are provided on an array type frame. Heat and pressure are apphed to the wavelength converting structures on the array type frame.
BRIEF DESCRIPTION OF THE DRAWINGS
[0004] FIG. 1 is a flow diagram of an example method of manufacturing a light emitting device (LED);
[0005] FIGs. 2A, 2B, 2C, 2D, 2E, 2F and 2G are diagrams of the example LED at various stages during the manufacturing process;
[0006] FIG. 3A is a diagram of an example LED die;
[0007] FIG. 3B is a diagram of an example light emitting semiconductor structure that may be included in the LED die of FIG. 3A; and
[0008] FIG. 3C is a diagram of an example LED that may include the LED die of FIG. 3A.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0009] Applications, such as the camera flash, automotive lighting and general hghting mentioned above, may make use of light emitting devices (LEDs) as white hght sources. Such LEDs may be referred to as white LEDs. White LEDs may appear to emit white light from the perspective of the viewer when the LEDs are in an on state. However, they may actually be made up of light emitting semiconductor structures that emit non-white pump light (e.g., blue or UV hght) as well as wavelength converting structures that make the non white pump hght appear white to the viewer.
[0010] In some applications, such as where arrays of LEDs are used, it may be desirable to prevent un-converted pump light and converted light from seeping through lateral sides of the LEDs and, for example, into adjacent LEDs. In such applications, reflectors may sometimes be disposed adjacent the side edges of each LED to prevent hght from escaping the LED through the sides. Conventionally, these reflectors are thick (e.g., over 25 microns thick) to prevent
the pump light from seeping through. However, it may also be possible to coat the side surfaces of LEDs with a non-metallic, thin film reflector, such as a Bragg reflector, which may be much thinner (e.g., 1-10 microns thick). Use of non-metallic, thin film reflectors may be desirable in applications such as where close placement of LEDs is required.
[0011] Non-metallic, thin film reflectors are typically made from materials, such as AlOx, Ti02, Ta02, Si02, Nb205, etc., which have low coefficients of thermal expansion (“CTE”s ~6-20ppm) in comparison to materials, such as phosphor in glass or ceramic phosphor, that conventionally form the wavelength converting structures. If a non-metalhc, thin film reflector is coated on side surfaces of an LED that includes a light emitting semiconductor structure and a wavelength converting structure, the non-metalhc, thin film reflector may crack due to CTE mismatch between the non-metalhc, thin film reflector and the wavelength converting structure.
[0012] In embodiments described herein, wavelength converting structures may be formed from a wavelength converting material that is highly loaded and has a better CTE match with non-metalhc, thin film reflector materials than the conventional wavelength converting materials described above. Such highly loaded wavelength converting material may be a molding compound formed from a binder or matrix material, such as silicone, that is highly loaded with phosphor particles as well as solid particles of a non-luminescent material, such as sihca (Si02 in amorphous or crystalline form). A concentration of solids (the phosphor and sohd, non-luminescent particles) in the molding compound may be 60% - 90% by volume.
[0013] While such a highly loaded wavelength converting material may provide a better CTE match for non-metallic, thin film reflector materials, due to the high concentration by volume of sohds in the wavelength converting molding compound, when the material is sawed into individual wavelength converting structures for attachment to individual LED dies, the edges become rough (e.g., 300-1,000 or more nm roughness). Phosphor structures with such highly rough side edges may be incompatible for use in conjunction with non-metallic, thin film reflectors because the highly rough side surfaces will cause light incident
thereon to re-direct and leak through the non-metalhc, thin film reflector and out through the side surfaces of the LED. Embodiments described herein provide methods whereby a highly loaded wavelength converting structure, such as described above, may be manufactured to have sufficiently smooth side surfaces (e.g., 100 nm roughness or less). While embodiments are described herein with respect to a highly loaded wavelength converting material, one of ordinary skill in the art will recognize that the methods described herein may be used with any type of wavelength converting structure where surface smoothness is desirable.
[0014] FIG. 1 is a flow diagram 100 of an example method of manufacturing an LED. FIGs. 2A, 2B, 2C, 2D, 2E, 2F and 2G are diagrams of the example LED at various stages during the manufacturing process.
[0015] In the example illustrated in FIG. 1, a layer of wavelength converting material is provided on a temporary tape (102). The wavelength converting material may be a molding compound formed from a binder or matrix material, such as silicone, that is highly loaded with phosphor particles as well as solid particles of a non-luminescent material, such as sihca (S1O2). A concentration of solids (the phosphor and non-luminescent particles) in the molding compound may be between 60 and 90% by volume. In one embodiment, the concentration of sohds (the phosphor and non-luminescent particles) in the molding compound is greater than 70% by volume. In another embodiment, the concentration of solids in the molding compound is greater than 80% by volume. In another embodiment, the concentration of solids in the molding compound is about 90% by volume. The temporary tape may be any suitable sawing tape. FIG. 2A is a diagram of an example 200A of a layer of a wavelength converting material 204 disposed on a temporary tape 202.
[0016] In embodiments, the wavelength converting material may be formed for use with a semiconductor structure that emits blue light. In such embodiments, the wavelength converting material may include, for example, particles of a yellow emitting wavelength converting material or green and red emitting wavelength converting materials, which will produce white light when the light emitted by the respective phosphors combines with the blue hght emitted by the light emitting semiconductor structure. In other embodiments,
the wavelength converting material may be formed for use with a semiconductor structure that emits UV light. In such embodiments, the wavelength converting material may include, for example, particles of blue and yellow wavelength converting materials or particles of blue, green and red wavelength converting materials. Wavelength converting particles emitting other colors of light may be added to tailor the spectrum of light emitted from the LED.
[0017] In embodiments, the luminescent, solid particles in the wavelength converting material may be composed of U3A1dOΐ2:Ob3+. The luminescent, sohd particles may be an amber to red emitting rare earth metal-activated oxonitridoalumosilicate of the general formula (Cai.x.y.zSrxBayMgz)i.n(Ali. a+bBa)Sii-bN3-bOb:REn wherein 0<x<l, 0<y<l, 0<z<l, 0<a<l, 0<b<l and
0.002<n<0.2, and RE may be selected from europium(II) and cerium(III).
[0018] In other embodiments, the luminescent, sohd particles in the wavelength converting material may include aluminum garnet phosphors with the general formula (Lui.x.y.a.bYxGdy)3(Ali.zGaz)50i2: CeaPrb, wherein 0<x<l, 0<y<l, 0<z<0.1, 0<a<0.2 and 0<b<0.1, such as Lu3Al50i2:Ce3+ and U3A1dOΐ2:Ob3+, which emits light in the yellow-green range; and (Sri.x.yBaxCay)2-zSi5-aAlaN8- aOa:Euz 2+, wherein 0<a<5, 0<x<l, 0<y<l, and 0<z<l such as Sr2Si5Ns:Eu2+, which emits hght in the red range. Other green, yellow and red emitting phosphors may also be suitable, including (Sri.a.bCabBac)SixNyOz:Eua 2+; (a=0.002-0.2, b=0.0- 0.25, c=0.0-0.25, x=1.5-2.5, y=1.5-2.5, z=1.5-2.5) including, SrSi2N202:Eu2+; (Sri-U- v-xMguCavBax)(Ga2-y-zAlyInzS4):Eu2+ including, for example, SrGa2S4:Eu2+; Sri. xBaxSi04:Eu2+; and (Cai-xSrx)S:Eu2+ wherein 0<x<l including, CaS:Eu2+ and SrS:Eu2+. Other suitable phosphors include, CaAlSiN3:Eu2+,(Sr,Ca)AlSiN3:Eu2+, and (Sr, Ca, Mg, Ba, Zn)(Al, B, In, Ga)(Si, Ge)N3:Eu2+.
[0019] In other embodiments, the luminescent, sohd particles in the wavelength converting material may also have a general formula (Sri.a. bCabBacMgdZne)SixNyOz:Eua 2+, wherein 0.002<a<0.2, 0.0<b<0.25, 0.0<c<0.25, 0.0<d<0.25, 0.0<e<0.25, 1.5<x<2.5, 1.5<y<2.5 andl.5<z<2.5. The luminescent, solid particles in the wavelength converting material may also have a general formula of MmAaBbOoNn:Zz where an element M is one or more bivalent elements, an element A is one or more trivalent elements, an element B is one or
more tetravalent elements, O is oxygen that is optional and may not be in the phosphor plate, N is nitrogen, an element Z that is an activator, n=2/3m+a+4/3b-2/3o, wherein m, a, b can all be 1 and o can be 0 and n can be 3. M is one or more elements selected from Mg (magnesium), Ca (calcium), Sr (strontium), Ba (barium) and Zn (zinc), the element A is one or more elements selected from B (boron), A1 (aluminum), In (indium) and Ga (gallium), the element B is Si (sihcon) and/or Ge (germanium), and the element Z is one or more elements selected from rare earth or transition metals. The element Z is at least one or more elements selected from Eu (europium), Mg (manganese), Sm (samarium) and Ce (cerium). The element A can be A1 (aluminum), the element B can be Si (silicon), and the element Z can be Eu (europium).
[0020] The luminescent, solid particles in the wavelength converting material may also be an Eu2+ activated Sr— SiON having the formula (Sri-a- bCabBac)SixNyOx:Eua, wherein a=0.002-0.2, b=0.0-0.25, c=0.0-0.25, x=1.5-2.5, y=1.5-2.5.
[0021] The luminescent, solid particles in the wavelength converting material may also be a chemically-altered Ce: YAG (Yttrium Aluminum Garnet) phosphor that is produced by doping the Ce: YAG phosphor with the trivalent ion of praseodymium (Pr). The luminescent, solid particles in the wavelength converting material may include a main fluorescent material and a supplemental fluorescent material. The main fluorescent material may be a Ce: YAG phosphor and the supplementary fluorescent material may be europium (Eu) activated strontium sulfide (SrS) phosphor (“Eu:SrS”). The main fluorescence material may also be a Ce: YAG phosphor or any other suitable yellow-emitting phosphor, and the supplementary fluorescent material may also be a mixed ternary crystalline material of calcium sulfide (CaS) and strontium sulfide (SrS) activated with europium ((CaxSri x)S:Eu2+). The main fluorescent material may also be a Ce:YAG phosphor or any other suitable yellow-emitting phosphor, and the supplementary fluorescent material may also be a nitrido-sihcate doped with europium. The nitrido-silicate supplementary fluorescent material may have the chemical formula (Sri.x.y.zBaxCay)2Si5N8:Euz 2+ where 0<x, y<0.5 and 0<z<0.1.
[0022] In embodiments, the luminescent, solid particles in the wavelength converting material may include strontium -lithium -aluminum: europium (II) ion (SrLiAh N4:Eu2+) class (also referred to as SLA), including MLiAl3N4: Eu2+ (M = Sr, Ba, Ca, Mg). In a specific embodiment, the luminescent particles may be selected from the following group of luminescent material systems: MLiAl3N4:Eu (M=Sr, Ba, Ca, Mg), M2Si04:Eu (M=Ba, Sr, Ca) , MSei-xSx:Eu (M=Sr, Ca, Mg), MSr2S4:Eu (M=Sr, Ca), M2SiF6:Mn (M=Na, K, Rb), M2TiF6:Mn (M=Na, K, Rb), MSiAlN3:Eu (M=Ca, Sr), M8Mg(Si04)4Cl2:Eu (M=Ca, Sr), M3MgSi208:Eu (M=Sr, Ba, Ca), MSi202N2:Eu (M=Ba, Sr, Ca), M2Si6.xAlxOxN8.x:Eu (M=Sr, Ca, Ba). However, other systems may also be of interest and may be protected by a coating. Also combinations of particles of two or more different luminescent materials may be applied, such as e.g. a green or a yellow luminescent material in combination with a red luminescent material.
[0023] In embodiments, the wavelength converting material may include a blend of any of the above-described phosphors.
[0024] Materials and concentrations of the non-luminescent, solid particles may be chosen at least in part based on the chosen phosphor or phosphors such that the molding compound has a CTE that matches or closely matches the CTE of a non-metallic, thin film reflector that is to be coated on side surfaces of the light emitting semiconductor structure and wavelength converting structure. The CTE of the molding compound can be around 20PPM if the loading is close to 90%. Further, in order to maximize the optical performance, by minimizing the scattering in the molding compound, the refraction index of the inert material may be matched as close as possible to the refraction index of the binder. For example, the refraction index of the binder may be 1.5, and the refraction index of the Si02 is 1.46. For another example, a binder with a refraction index of 1.41 may be used in combination with Si02. The volume % may calculated by taking into account of the mass of each of the solid components plus the mass of the binder divided and the specific gravity of each component.
[0025] Referring back to FIG. 1, the layer of the wavelength converting material may be sawed or otherwise separated into individual wavelength
converting structures (104). FIG. 2B is a diagram of an example of the individual wavelength converting structures 204 disposed on the temporary tape 202 after sawing or separation. Both a side view 200B and a top view 200C of the tape 202 are provided in FIG. 2B. In the side view 200B, five wavelength converting structures 204A, 204B, 204C, 204D and 204E are shown provided on the temporary tape 202. In the top view 200C, nine wavelength converting structures are shown, including the wavelength converting structures 204A, 204B and 204C. While five and nine wavelength converting structures are illustrated in views 200B and 200C in FIG. 2B, one of ordinary skill in the art will recognize that the wavelength converting layer 204 may be separated into any number of wavelength converting structures on the temporary tape 202 within the scope of the embodiments described herein. As mentioned above, at this point in the process, due, for example, to displacement of particles in the highly loaded wavelength converting molding compound, side edges (e.g., 250A, 250B, 250C and 250D as labeled for one of the wavelength converting structures in top view 200C of FIG. 2B) may have an undesirably high roughness, such as 300-1,000 or more nm roughness.
[0026] The individual wavelength converting structures may be transferred from the temporary tape 202 (106). FIGs. 2C and 2D are diagrams 200D and 200E showing the wavelength converting structures 204A, 204B and 204C after transfer. In the example illustrated in FIG. 2C, the wavelength converting structures 204A, 204B and 204C are provided on a structure, which may be formed from a metal frame 210 that is adhered to another tape 206, such as a Kapton tape, via a thermal release tape or layer 208. In the example illustrated in FIG. 2D, the frame 210 includes raised regions that define recessed areas 260 in which respective wavelength converting structures are to be compressed. While not visible in the side view in FIG. 2D, the raised regions may form an array such that each individual wavelength converting structure is disposed in a respective recessed area 260 in the frame 210. A release film 214 may be stretched over the frame 210 and the individual wavelength converting structures 204A, 204B and 204C.
[0027] The individual wavelength converting structures may be compression molded on the tape 206 and within the frame 210 (108). In embodiments, the structure, including the tape 206, the thermal release tape or layer 208, and the metal frame 210 may be placed within a diaphragm 216 and subjected to pressure and heat sufficient to cause the individual wavelength converting structures to flow within the respective recessed areas 260A, 260B and 260C. In embodiments, an effective pressure may be in a range of 0.7- 0.8Mpa and an effective heat may be in a range of 50-90°C.
[0028] FIG. 2E is a diagram 200F of the wavelength converting structures after compression using the diaphragm 216. As illustrated, individual wavelength converting structures 218A, 218B and 218C take the shape of the respective recessed areas 260A, 260B and 260C in which they are disposed. The raised portions of the frame 210 may have smooth inner walls 213 such that the individual wavelength converting structures 218, after compression, will have smooth edges (e.g., 100 nm roughness or less) that are, for example, suitable for use with a thin film reflector such as a Bragg reflector (not shown).
[0029] A respective light emitting die may be attached to each individual wavelength converting structure (110). In embodiments, the wavelength converting molding compound may have enough adhesion such that the hght emitting dies may be attached thereto without any additional adhesive. The dice may thus be attached using heat to the individual wavelength converting structures, such as by using the heated collet of a die attach machine. Conventionally, a wavelength converting structure would be attached to a die using some type of intervening adhesive material, which may cause wave guiding at the interface with the adhesive material. Because the wavelength converting structures formed using the above-mentioned materials and using the methods described above may have sufficient adhesion such that the intervening adhesive material is not needed, such light guiding may be eliminated, further reducing the potential for hght leakage through the sides of the LEDs and any thin film reflector coated thereon.
[0030] The dies may then be cured, for example, at a temperature of 150°C over eight hours. FIG. 2F is a diagram 200G of individual LEDs 270A, 270B and
270C after attaching the light emitting dies 230A, 230B and 230C to their respective wavelength converting structures 218A, 218B and 218C and subsequent curing. The individual LEDs 270A, 270B and 270C may then be released from the frame 210, for example, by heating the thermal release tape or layer 208 (112). FIG. 2G is a diagram 200H showing LEDs 270A, 270B and 270C, attached to the tape 206, formed by the method 100.
[0031] FIG. 3A is a diagram of an example LED die 230 that may be attached to a wavelength converting structure, as described above. In the example illustrated in FIG. 3A, the LED die 230 includes a hght emitting semiconductor structure 302. Contacts 304 and 306 may be coupled to the light emitting semiconductor structure 302, either directly or via another structure such as a submount, for electrical connection to a circuit board or other substrate or device. In embodiments, the contacts 304 and 306 may be electrically insulated from one another by a gap 308, which may be filled with a dielectric material.
[0032] The light emitting semiconductor structure 302 may be any light emitting semiconductor structure that emits light that may be converted to light having a different color point via a wavelength converting material. For example, the light emitting semiconductor structure 302 may be formed from III- V semiconductors including, but not limited to, AIN, A1P, ALAs, AlSb, GaN, GaP, GaAs, GaSb, InN, InP, InAs, InSb, II-VI semiconductors including, but not limited to, ZnS, ZnSe, CdSe, CdTe, group IV semiconductors including, but not limited to Ge, Si, SiC, and mixtures or alloys thereof. These example semiconductors have indices of refraction ranging from about 2.4 to about 4.1 at the typical emission wavelengths of LEDs in which they are present. For example, Ill-Nitride semiconductors, such as GaN, have refractive indices of about 2.4 at 500 nm, and Ill-Phosphide semiconductors, such as InGaP, have refractive indices of about 3.7 at 600 nm. Contacts 304 and 306 may be formed from a solder, such as AuSn, AuGa, AuSi or SAC solders.
[0033] FIG. 3B is a diagram of an example light emitting semiconductor structure 302 that may be included in the LED die 230 of FIG. 3A. The illustrated example is a flip chip structure. However, one of ordinary skill in the
art will understand that the embodiments described herein may be applied to other types of LED designs, such as vertical, lateral, and multi- junction devices.
[0034] In the example illustrated in FIG. 3B, the light emitting semiconductor structure 302 includes a hght emitting active region 312 disposed between a semiconductor layer or region of n-type conductivity (also referred to as an n-type region) 310 and a semiconductor layer or region of p-type conductivity (also referred to as a p-type region) 314. Contacts 316 and 318 are disposed in contact with a surface of the light emitting semiconductor structure 302 and electrically insulated from one another by a gap 320, which may be filled by a dielectric material, such as an oxide or nitride of sihcon (i.e., S1O2 or S13N4). In the illustrated embodiment, contact 316 (also referred to as a p-contact) is in direct contact with a surface of the p-type region 314, and the contact 318 (also referred to as an n-contact) is in direct contact with a surface of the n-type region 310. Although not shown in FIG. 3B, a dielectric material, such as disposed in the gap 320, may also line side walls of the hght emitting active region 312 and p-type region 314 to electrically insulate those regions from the contact 318 to prevent shorting of the p-n junction.
[0035] The n-type region 310 may be grown on a growth substrate and may include one or more layers of semiconductor material. Such layer or layers may include different compositions and dopant concentrations including, for example, preparation layers, such as buffer or nucleation layers, and/or layers designed to facilitate removal of the growth substrate. These layers may be n-type or not intentionally doped, or may even be p-type device layers. The layers may be designed for particular optical, material, or electrical properties desirable for the light emitting region to efficiently emit hght. Like the n-type region 310, the p- type region 314 may include multiple layers of different composition, thickness, and dopant concentrations, including layers that are not intentionally doped, or n-type layers. While layer 310 is described herein as the n-type region and layer 314 is described herein as the p-type region, the n-type and p-type regions could also be switched without departing from the scope of the embodiments described herein.
[0036] The light emitting active region 312 may be, for example, a p-n diode junction associated with the interface of p-region 314 and n-region 310. Alternatively, the light emitting active region 312 may include one or more semiconductor layers that are doped n-type or p-type or are un-doped. For example, the light emitting active region 312 may include a single thick or thin light emitting layer. This includes a homojunction, single heterostructure, double heterostructure, or single quantum well structure. Alternatively, the light emitting active region 312 may be a multiple quantum well light emitting region, which may include multiple quantum well light emitting layers separated by barrier layers.
[0037] The p-contact 316 may be formed on a surface of the p-type region
314. The p-contact 316 may include multiple conductive layers, such as a reflective metal and a guard metal, which may prevent or reduce electromigration of the reflective metal. The reflective metal may be silver or any other suitable material, and the guard metal may be TiW or TiWN. The n- contact 318 may be formed in contact with a surface of the n-type region 310 in an area where portions of the active region 312, the n-type region 310, and the p- contact 316 have been removed to expose at least a portion of the surface of the n-type region 310. The sidewall of the exposed mesa or via may be coated with a dielectric to prevent shorting. The contacts 316 and 318 may be, for example, metal contacts formed from metals including, but not limited to, gold, silver, nickel, aluminum, titanium, chromium, platinum, palladium, rhodium, rhenium, ruthenium, tungsten, and mixtures or alloys thereof. In other examples, one or both contacts 316 and 318 may be formed from transparent conductors, such as indium tin oxide.
[0038] The n-contact 318 and p-contact 316 are not limited to the arrangement illustrated in FIG. 3B and may be arranged in any number of different ways. In embodiments, one or more n-contact vias may be formed in the light emitting semiconductor structure 302 to make electrical contact between the n-contact 318 and the n-type layer 310. Alternatively, the n-contact 318 and p-contact 316 may be redistributed to form bond pads with a dielectric/metal stack as known in the art. The p-contact 316 and the n-contact
318 may be electrically connected to the contacts 304 and 306 of FIG. 3A, respectively, either directly or via another structure, such as a submount.
[0039] FIG. 3C is a diagram of an example LED 330. In the example illustrated in FIG. 3C, the LED 330 includes an LED die 230. A wavelength converting structure 218 is disposed in direct contact with a surface 352 of the LED die 230. A thin film reflector 360, such as a Bragg reflector, may be a coating on side surfaces 370 of a structure formed from the LED die 230 and the wavelength converting structure 218 such that the thin film reflector 360 may be in direct contact with side surfaces of both the wavelength converting structure 218 and the LED die 230. The wavelength converting structure 218 having properties such as described above has sufficient CTE match with the thin film reflector 360 such that the thin film reflector 360 does not crack when in direct contact with the wavelength converting structure 218. Further, the wavelength converting structure 218 may have a roughness of 100 nm or less, as described in detail above, which is sufficient for use with the thin film reflector 360 such that un-converted pump light and converted light do not leak through the side surfaces 370 and through the thin film reflector 360.
[0040] Having described the embodiments in detail, those skilled in the art will appreciate that, given the present description, modifications may be made to the embodiments described herein without departing from the spirit of the inventive concept. Therefore, it is not intended that the scope of the invention be limited to the specific embodiments illustrated and described.
k k k
Claims
1. A method of manufacturing a light emitting device (LED), the method comprising:
providing a layer of a wavelength converting material, the wavelength converting material comprising at least a binder or matrix material, particles of a non-luminescent material, and phosphor particles, the wavelength converting material having a concentration of greater than 60% by volume of the non- luminescent material and phosphor particles;
separating the layer of the wavelength converting material into a plurality of wavelength converting structures, one of the plurahty of wavelength
converting structures having a first surface, a second surface opposite the first surface, and side surfaces created by the separation, the side surfaces
interconnecting the first surface and the second surface;
placing one of the plurahty of wavelength converting structures in a frame having an interior area defined by one or more surfaces of the frame; and
applying sufficient heat and pressure to the one wavelength converting structure to cause the wavelength converting material in the structure to flow, to cover the interior area, and to contact a surface of the frame to create a new wavelength converting structure side surface.
2. The method of claim 1, wherein the new side surface has a roughness of less than 100 nm.
3. The method of claim 1, further comprising attaching a light emitting die to the one wavelength converting structure without using adhesive.
4. The method of claim 1, wherein the concentration of non- luminescent and phosphor particles in the wavelength converting material is greater than 70% by volume.
5. The method of claim 1, wherein the concentration of non- luminescent and phosphor particles in the wavelength converting material is about 90% by volume.
6. The method of claim 1, further comprising coating the new side surface with a thin film of a non-metalhc reflector.
7. The method of claim 6, wherein the non-metallic reflector is a Bragg reflector with a thickness of 1-10 microns.
8. The method of claim 6, wherein both the wavelength converting material and the non-metallic reflector have a coefficient of thermal expansion between 6 and 20ppm.
9. The method of claim 1, wherein the binder or matrix material is silicone and the non-luminescent material is silica (S1O2).
10. The method of claim 1, wherein applying sufficient heat and pressure comprises heating the one wavelength converting structure to a temperature of between 50°C and 90°C and applying a pressure of between 0.7 and 0.8 Mpa.
11. The method of claim 1, wherein separating the layer of the wavelength converting material comprises sawing the layer of the wavelength converting material.
12. A light emitting device (LED) comprising:
a hght emitting semiconductor structure comprising a light-emitting active layer disposed between an n-layer and a p-layer;
a wavelength converting material having a first surface adjacent the hght emitting semiconductor structure, a second surface opposite the first surface, and a plurality of side surfaces, the wavelength converting material comprising at
least a binder or matrix material, particles of a non-luminescent material, and phosphor particles, the wavelength converting material having a concentration of greater than 60% by volume of the non-luminescent material and phosphor particles and having side surfaces with a roughness of less than 100 nm.
13. The LED of claim 12, wherein the first surface of the wavelength converting material is in direct contact with the light emitting semiconductor structure without intervening adhesive.
14. The LED of claim 12, wherein the light emitting semiconductor structure has a first surface, a second surface opposite the first surface, and a plurality of side surfaces, and the LED further comprises a non-metalhc, thin- film reflector in direct contact with the plurahty of side surfaces of the light emitting semiconductor structure and the wavelength converting material.
15. The LED of claim 14, wherein the thin film reflector is a Bragg reflector and has a thickness of 1-10 microns.
16. The LED of claim 14, wherein both the wavelength converting material and the thin film reflector have a CTE between 6 and 20ppm
17. The LED of claim 12, wherein the binder or matrix material is silicone and the non-luminescent material is silica (S1O2).
18. The LED of claim 12, wherein the concentration of non-luminescent and phosphor particles in the wavelength converting material is greater than 70% by volume.
19. The LED of claim 12, wherein the concentration of non-luminescent and phosphor particles in the wavelength converting material is about 90% by volume.
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US16/142,247 | 2018-09-26 | ||
US16/142,247 US11183616B2 (en) | 2018-09-26 | 2018-09-26 | Phosphor converter structures for thin film packages and method of manufacture |
EP18205710 | 2018-11-12 | ||
EP18205710.9 | 2018-11-12 |
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Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20130187540A1 (en) * | 2012-01-24 | 2013-07-25 | Michael A. Tischler | Discrete phosphor chips for light-emitting devices and related methods |
EP2731152A2 (en) * | 2012-11-09 | 2014-05-14 | Nitto Denko Corporation | Phosphor layer-covered optical semiconductor element, producing method thereof, optical semiconductor device, and producing method thereof |
US20170365747A1 (en) * | 2013-04-08 | 2017-12-21 | Lumileds Llc | Led with high thermal conductivity particles in phosphor conversion layer |
-
2019
- 2019-09-24 WO PCT/IB2019/058106 patent/WO2020065539A1/en active Application Filing
- 2019-09-26 TW TW108134868A patent/TWI791901B/en active
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20130187540A1 (en) * | 2012-01-24 | 2013-07-25 | Michael A. Tischler | Discrete phosphor chips for light-emitting devices and related methods |
EP2731152A2 (en) * | 2012-11-09 | 2014-05-14 | Nitto Denko Corporation | Phosphor layer-covered optical semiconductor element, producing method thereof, optical semiconductor device, and producing method thereof |
US20170365747A1 (en) * | 2013-04-08 | 2017-12-21 | Lumileds Llc | Led with high thermal conductivity particles in phosphor conversion layer |
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TW202029530A (en) | 2020-08-01 |
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