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

• US 9,276,178 B2
• Filed: 02/17/2015
• Issued: 03/01/2016
• Est. Priority Date: 01/24/2012
• Status: Active Grant

• Current Assignee: Epistar Corporation
• Original Assignee: Cooledge Lighting Inc.
• Inventors: Tischler, Michael A.
• Primary Examiner(s): GREEN, TELLY D
• Application Number:
  US14/624,096
• Publication Number:
  US 20150162504A1
• Time in Patent Office: 378 Days
• Field of Search: 257/98, 257/89, 438/29, 438/27, 438/25, 438/28, 438/31, 313/512, 313/503, 313/501, 362/231, 362/97, 362/237, 362/606
• US Class Current: 1/1
• 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., 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 plurality of semiconductor dies each suspended in cured polymeric binder, the method comprising:

forming a plurality of semiconductor dies on a substrate wafer;

disposing the substrate wafer over a mold substrate, each semiconductor die (i) having at least two spaced-apart contacts adjacent the mold substrate, and (ii) being a bare-die light-emitting element;

removing at least a portion of the substrate wafer from the semiconductor dies;

coating the semiconductor dies with a polymeric binder;

curing the polymeric binder; and

separating the coated semiconductor dies from the mold substrate,

wherein (i) the contacts of each semiconductor die remain at least partially uncoated by the polymeric binder and (ii) the polymeric binder is transparent to a wavelength of light emitted by the semiconductor dies.

2. The method of claim 1, wherein 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 light and unconverted light emitted by the semiconductor dies combining to form mixed light.

3. The method of claim 2, further comprising forming a reflecting layer over or within at least a portion of the polymeric binder, 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 and/or the light emitted by the wavelength-conversion material.

4. The method of claim 3, wherein the reflecting layer comprises at least one of (i) a reflecting film or (ii) a plurality of particles.

5. The method of claim 2, wherein the mixed light comprises substantially white light.

6. The method of claim 5, wherein the substantially white light has a correlated color temperature in the range of 2000 K to 10,000 K.

7. The method of claim 5, wherein a variation in color temperature of the substantially white light emitted when each semiconductor die is individually energized is less than four MacAdam ellipses across the plurality of coated semiconductor dies.

8. The method of claim 5, wherein a variation in color temperature of the substantially white light emitted when each semiconductor die is individually energized is less than two MacAdam ellipses across the plurality of coated semiconductor dies.

9. The method of claim 5, wherein a variation in color temperature of the substantially white light emitted when each semiconductor die is individually energized is less than 500 K across the plurality of coated semiconductor dies.

10. The method of claim 2, wherein the polymeric binder comprises a plurality of discrete regions, at least one of which comprises the polymeric binder without the wavelength-conversion material.

11. The method of claim 1, wherein separating the coated semiconductor dies from the mold substrate comprises (i) separating the cured polymeric binder from the mold substrate, and (ii) dividing the cured polymeric binder into a plurality of discrete portions at least one of which comprises at least one semiconductor die coated with cured polymeric binder.

12. The method of claim 11, wherein the cured polymeric binder is divided before separating the cured polymeric binder from the mold substrate.

13. The method of claim 11, wherein the cured polymeric binder is divided after separating the cured polymeric binder from the mold substrate.

14. The method of claim 11, wherein after dividing the cured polymeric binder into the plurality of discrete portions, a volume of polymeric binder surrounding each portion is substantially equal.

15. The method of claim 11, wherein each discrete portion contains only one semiconductor die.

16. The method of claim 11, wherein each discrete portion is a rectangular solid having approximately 90°

corners between adjacent faces thereof.

17. The method of claim 11, 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.

18. The method of claim 17, 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, an anisotropic conductive adhesive, or solder.

19. The method of claim 17, further comprising electrically connecting the at least one semiconductor die to circuitry for powering the at least one semiconductor die.

20. The method of claim 1, wherein removing at least a portion of the substrate wafer from the semiconductor dies comprises separating the semiconductor dies from each other before the semiconductor dies are coated with the polymeric binder.

21. The method of claim 1, further comprising dividing the substrate wafer into discrete substrate-wafer portions before at least a portion of the substrate wafer is removed from the semiconductor dies, at least one of the substrate-wafer portions comprising at least one semiconductor die.

22. The method of claim 1, further comprising dividing the substrate wafer into discrete substrate-wafer portions after at least a portion of the substrate wafer is removed from the semiconductor dies, at least one of the substrate-wafer portions comprising at least one semiconductor die.

23. The method of claim 1, wherein removing at least a portion of the substrate wafer from the semiconductor dies comprises removing substantially all of the substrate wafer from the semiconductor dies.

24. The method of claim 1, wherein each semiconductor die comprises a plurality of semiconductor layers collectively defining a light-emitting element.

25. The method of claim 24, wherein removing at least a portion of the substrate wafer from the semiconductor dies comprises removing substantially all of the substrate wafer from the plurality of semiconductor layers.

26. The method of claim 24, wherein forming the plurality of semiconductor dies comprises, for at least one of the semiconductor dies, (i) removing a portion of at least one of the semiconductor layers to form a non-planar top surface, and (ii) forming one of the contacts where the portion of the at least one of the semiconductor layers was removed.

27. The method of claim 24, wherein at least one of the semiconductor layers comprises at least one of silicon, GaAs, InAs, AlAs, InP, GaP, AlP, InSb, GaSb, AlSb, GaN, InN, AlN, SiC, ZnO, or an alloy or mixture thereof.

28. The method of claim 1, further comprising forming a reflecting layer over or within at least a portion of the polymeric binder, 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.

29. The method of claim 1, wherein a spacing between neighboring semiconductor dies is substantially constant across the cured polymeric binder.

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

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

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

33. The method of claim 32, wherein curing the binder adheres the array of optical elements to the cured binder.

34. The method of claim 32, further comprising dividing the cured polymeric binder into a plurality of discrete portions, at least one of which comprises (i) at least one semiconductor die coated with cured polymeric binder and (ii) at least one optical element.

35. The method of claim 1, wherein the at least a portion of the substrate wafer is removed from the semiconductor dies by at least one of chemical etching, laser lift-off, exfoliation, mechanical grinding, or chemical-mechanical polishing.

36. The method of claim 1, wherein the substrate wafer comprises a semiconductor substrate.

37. The method of claim 1, wherein the substrate wafer comprises GaAs, GaP, silicon, or sapphire.

38. The method of claim 1, further comprising:

before separating the coated semiconductor dies from the mold substrate, disposing a second substrate in contact with the plurality of semiconductor dies coated with polymeric binder,

wherein, when the coated semiconductor dies are separated from the mold substrate, the coated semiconductor dies remain in contact with the second substrate.

39. The method of claim 38, further comprising separating the coated semiconductor dies from the second substrate.

40. 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.

41. 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.

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

43. 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.

44. The method of claim 43, wherein curing the polymeric binder comprises:

at least partially curing the polymeric binder; and

thereafter, removing the mold substrate from the mold.

45. The method of claim 43, 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.

46. The method of claim 45, wherein each compartment imparts a complementary shape to a portion of the polymeric binder, the complementary shapes being substantially identical to each other.

47. 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.

48. The method of claim 47, 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.

49. The method of claim 47, further comprising disposing a mold cover over and in contact with at least a portion of the polymeric binder.

50. The method of claim 49, 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.

51. The method of claim 50, wherein each compartment imparts a complementary shape to a portion of the polymeric binder, the complementary shapes being substantially identical to each other.