Light-emitting dies incorporating wavelength-conversion materials and related methods

• US 8,759,125 B2
• Filed: 01/24/2013
• Issued: 06/24/2014
• Est. Priority Date: 01/24/2012
• Status: Active Grant

• Current Assignee: Epistar Corporation (Ennostar, Inc.)
• Original Assignee: Cooledge Lighting Inc.
• Inventors: Tischler, Michael A.
• Primary Examiner(s): GREEN, TELLY D
• Application Number:
  US13/748,864
• Publication Number:
  US 20130187178A1
• Time in Patent Office: 516 Days
• Field of Search: 257/98, 257/89, 438/27, 438/29, 438/25, 438/28, 438/31, 313/503, 313/501, 313/512, 362/231, 362/97, 362/3, 362/237, 362/606
• US Class Current: 438/27
• CPC Class Codes: H01L 21/00 Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
• CPC Class Codes: H01L 2224/13022 the bump connector being at least partially embedded in the surface
• CPC Class Codes: H01L 2224/16145 the bodies being stacked
• CPC Class Codes: H01L 2224/73259 Bump and HDI connectors
• CPC Class Codes: H01L 24/96 the devices being encapsulated in a common layer, e.g. neo-wafer or pseudo-wafer, said common layer being separable into individual assemblies after connecting
• CPC Class Codes: H01L 24/97 the devices being connected to a common substrate, e.g. interposer, said common substrate being separable into individual assemblies after connecting
• CPC Class Codes: H01L 25/00 Assemblies consisting of a plurality of individual semiconductor or other solid state devices ; Multistep manufacturing processes thereofdevices consisting of a plurality of solid state components formed in or on a common substrate H01L27/00; photovoltaic modules or arrays of photovoltaic cells H01L31/042 ; panels or arrays of photo electrochemical cells H01G9/2068
• CPC Class Codes: H01L 25/0753 the devices being arranged next to each other
• CPC Class Codes: H01L 27/14 including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation radiation-sensitive components structurally associated with one or more electric light sources only H01L31/14; couplings of light guides with optoelectronic elements G02B6/42
• CPC Class Codes: H01L 29/00 Semiconductor devices specially adapted for rectifying, amplifying, oscillating or switching and having potential barriers; Capacitors or resistors having potential barriers, e.g. a PN-junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor H01L31/00 - H01L33/00, H10K10/00, H10N take precedence; details other than of semiconductor bodies or of electrodes thereof H01L23/00; devices consisting of a plurality of solid state components formed in or on a common substrate H01L27/00
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/01005 Boron [B]
• CPC Class Codes: H01L 2924/07802 not being an ohmic electrical conductor
• CPC Class Codes: H01L 2924/07811 Extrinsic, i.e. with electrical conductive fillers
• CPC Class Codes: H01L 2924/12032 Schottky diode
• CPC Class Codes: H01L 2924/12041 LED
• CPC Class Codes: H01L 2924/12042 LASER
• CPC Class Codes: H01L 2924/12043 Photo diode
• CPC Class Codes: H01L 2924/181 Encapsulation
• CPC Class Codes: H01L 2924/1815 Shape
• CPC Class Codes: H01L 2933/0033 : relating to semiconductor body packages
• CPC Class Codes: H01L 2933/0041 : relating to wavelength conversion elements
• CPC Class Codes: H01L 31/0203 : Containers; Encapsulations , e.g. encapsulation of photodiodesfor photovoltaic devices H01L31/048; for organic photosensitive devices H10K30/80
• CPC Class Codes: H01L 31/022425 : for solar cells
• CPC Class Codes: H01L 31/02322 : comprising luminescent members, e.g. fluorescent sheets upon the device
• CPC Class Codes: H01L 31/02327 : the optical elements being integrated or being directly associated to the device, e.g. back reflectors optical coatings H01L31/0216
• CPC Class Codes: H01L 31/048 : Encapsulation of modules
• CPC Class Codes: H01L 31/055 : where light is absorbed and re-emitted at a different wavelength by the optical element directly associated or integrated with the PV cell, e.g. by using luminescent material, fluorescent concentrators or up-conversion arrangements
• CPC Class Codes: H01L 33/486 : adapted for surface mounting
• CPC Class Codes: H01L 33/501 : characterised by the materials, e.g. binder
• CPC Class Codes: H01L 33/505 : characterised by the shape, e.g. plate or foil
• CPC Class Codes: H01L 33/60 : Reflective elements
• CPC Class Codes: H05B 33/02 : Details
• CPC Class Codes: H05B 33/12 : Light sources with substantially two-dimensional radiating surfaces
• CPC Class Codes: Y02E 10/52 : PV systems with concentrators

Abstract

In accordance with certain embodiments, semiconductor dies are embedded within polymeric binder to form, e.g., freestanding white light-emitting dies and/or composite wafers containing multiple light-emitting dies embedded in a single volume of binder.

Claims

1. A method of forming a composite wafer comprising a plurality of discrete semiconductor dies suspended in a cured polymeric binder, the method comprising:

disposing the plurality of discrete semiconductor dies on a mold substrate, each semiconductor die (i) having at least two spaced-apart contacts adjacent the mold substrate, (ii) being spaced away from one or more neighboring semiconductor dies, and (iii) being a bare-die light-emitting element;

coating the plurality of semiconductor dies with a polymeric binder; and

curing the polymeric binder to form the composite wafer,

wherein the contacts of each semiconductor die remain at least partially uncoated by the polymeric binder, and wherein (i) the polymeric binder is transparent to a wavelength of light emitted by the semiconductor dies, and (ii) the polymeric binder contains a wavelength-conversion material for absorption of at least a portion of light emitted from the semiconductor dies and emission of converted light having a different wavelength, converted and unconverted light emitted by the semiconductor dies combining to form substantially white light having a correlated color temperature in the range of 2000K to 10,000K.

2. The method of claim 1, further comprising separating the composite wafer into a plurality of discrete portions each comprising at least one semiconductor die coated with cured polymeric binder.

3. The method of claim 2, wherein after separation a volume of polymeric binder surrounding each semiconductor die is substantially equal.

4. The method of claim 2, wherein each discrete portion of the composite wafer contains only one semiconductor die.

5. The method of claim 2, wherein each discrete portion of the composite wafer is a rectangular solid having approximately 90°

corners between adjacent faces thereof.

6. The method of claim 2, further comprising electrically coupling the contacts of the at least one semiconductor die in one of the discrete portions to spaced-apart conductive traces on a substrate.

7. The method of claim 6, wherein electrically coupling the contacts to the conductive traces comprises adhering the contacts to the conductive traces with at least one of a conductive adhesive, anisotropic conductive adhesive, or solder.

8. The method of claim 6, further comprising electrically connecting the at least one semiconductor die to circuitry for powering the at least one semiconductor die.

9. The method of claim 2, further comprising, after separating the composite wafer, removing additional material from each of the discrete portions, whereby each portion has a desired shape thereafter.

10. The method of claim 1, further comprising separating the composite wafer from the mold substrate.

11. The method of claim 1, further comprising:

disposing a second substrate in contact with the plurality of semiconductor dies coated with polymeric binder; and

removing the mold substrate from the plurality of semiconductor dies coated with polymeric binder, the plurality of semiconductor dies coated with polymeric binder remaining attached to the second substrate.

12. The method of claim 11, further comprising separating the composite wafer from the second substrate.

13. The method of claim 1, wherein, before curing the polymeric binder, the contacts of the plurality of semiconductor dies are at least partially embedded within the mold substrate.

14. The method of claim 1, wherein, after curing the polymeric binder, at least a portion of each of the contacts of the plurality of semiconductor dies protrudes from the cured binder.

15. The method of claim 1, wherein the polymeric binder comprises at least one of silicone or epoxy.

16. The method of claim 1, wherein coating the plurality of semiconductor dies with the polymeric binder comprises:

dispensing the polymeric binder into a mold; and

disposing the mold substrate over the mold, whereby the plurality of semiconductor dies are suspended within the polymeric binder.

17. The method of claim 16, wherein curing the polymeric binder comprises:

at least partially curing the polymeric binder; and

thereafter, removing the mold substrate from the mold.

18. The method of claim 16, wherein (i) the mold comprises a plurality of discrete compartments in which the polymeric binder is disposed, and (ii) one or more semiconductor dies are suspended within or above each compartment prior to curing the polymeric binder.

19. The method of claim 18, wherein each compartment imparts a complementary shape to a portion of the polymeric binder, the complementary shapes being substantially identical to each other.

20. The method of claim 1, wherein coating the plurality of semiconductor dies with the polymeric binder comprises dispensing the polymeric binder over the mold substrate, the polymeric binder being contained over the mold substrate by one or more barriers extending above a surface of the mold substrate.

21. The method of claim 20, wherein curing the polymeric binder comprises:

at least partially curing the polymeric binder; and

thereafter, removing the mold substrate from the plurality of semiconductor dies.

22. The method of claim 20, further comprising disposing a mold cover over and in contact with at least a portion of the polymeric binder.

23. The method of claim 22, wherein (i) the mold cover comprises a plurality of discrete compartments and (ii) one or more semiconductor dies are suspended within or beneath each compartment prior to curing the polymeric binder.

24. The method of claim 23, wherein each compartment imparts a complementary shape to a portion of the polymeric binder, the complementary shapes being substantially identical to each other.

25. The method of claim 1, wherein the variation in the color temperature of the substantially white light emitted when each semiconductor die is individually energized is less than four MacAdam ellipses across the composite wafer.

26. The method of claim 1, wherein the variation in the color temperature of the substantially white light emitted when each semiconductor die is individually energized is less than two MacAdam ellipses across the composite wafer.

27. The method of claim 1, wherein the variation in the color temperature of the substantially white light emitted when each semiconductor die is individually energized is less than 500 K across the composite wafer.

28. The method of claim 1, further comprising forming a reflecting layer over or within at least a portion of the composite wafer, wherein the reflecting layer has a reflectivity of at least 50% to a wavelength of light emitted by the semiconductor dies within the polymeric binder or the light emitted by the wavelength-conversion material.

29. The method of claim 28, wherein the reflecting layer comprises at least one of (i) a reflecting film or (ii) a plurality of particles.

30. The method of claim 1, wherein the composite wafer has a first surface and a second surface opposite the first surface, and the variation in thickness between the first and second surfaces is less than 10%.

31. The method of claim 1, wherein a spacing between neighboring semiconductor dies is substantially constant across the composite wafer.

32. The method of claim 1, wherein a thickness of the polymeric binder above each of the semiconductor dies is the same to within 5%.

33. The method of claim 1, wherein the polymeric binder comprises a plurality of discrete regions, at least one of which comprises the polymeric binder without the wavelength-conversion material.

34. The method of claim 1, wherein (i) at least one semiconductor die comprises one or more active layers over a substrate, and (ii) the substrate is partially or completely removed before coating with the polymeric binder.

35. The method of claim 34, wherein the substrate of the at least one semiconductor die is partially or completely removed after disposing the at least one semiconductor die on the mold substrate.

36. The method of claim 1, further comprising associating an optical element with one or more of the semiconductor dies.

37. The method of claim 1, further comprising disposing an array of optical elements on the binder prior to curing.

38. The method of claim 37, wherein curing the binder adheres the array of optical elements to the cured binder.

39. The method of claim 37, wherein the composite wafer comprises the array of optical elements, and further comprising separating the composite wafer into discrete portions each comprising at least one optical element.