Printing phosphor on LED wafer using dry film lithography

• US 8,900,892 B2
• Filed: 03/15/2013
• Issued: 12/02/2014
• Est. Priority Date: 12/28/2011
• Status: Active Grant

• Current Assignee: Ledengin, Inc. (Ams-Osram AG)
• Original Assignee: Ledengin, Inc. (Ams-Osram AG)
• Inventors: Mei, Zequn, Yan, Xianto
• Primary Examiner(s): TRINH, MICHAEL MANH
• Application Number:
  US13/842,127
• Publication Number:
  US 20130210179A1
• Time in Patent Office: 627 Days
• Field of Search: 438/22, 438/29, 438/26, 438/28, 438/99, 257/E21.032
• US Class Current: 438/22
• CPC Class Codes: H01L 2933/0041 relating to wavelength conversion elements
• CPC Class Codes: H01L 33/50 Wavelength conversion elements
• CPC Class Codes: H01L 33/505 characterised by the shape, e.g. plate or foil
• CPC Class Codes: H01L 33/508 having a non-uniform spatial arrangement or non-uniform concentration, e.g. patterned wavelength conversion layer, wavelength conversion layer with a concentration gradient of the wavelength conversion material

Abstract

A method for depositing a layer of phosphor-containing material on a plurality of LED (light-emitting diode) dies on a wafer includes disposing a layer of dry photoresist film over a plurality of LED dies on a wafer, disposing a mask layer over the dry photoresist film, and patterning the dry photoresist film to form a plurality of openings in the dry photoresist film to expose a top surface of each of the LED dies. The method also includes depositing a phosphor-containing material on the exposed top surface of each the LED dies using a screen printing process, and removing the patterned dry photoresist film.

Claims

1. A method for depositing a layer of phosphor-containing material on a plurality of LED (light-emitting diode) dies on a wafer, the method comprising:

disposing a layer of dry photoresist film over a plurality of LED dies on a wafer, a bottom surface of the dry photoresist film being substantially aligned to top surfaces of the LED dies;

disposing a mask layer over the dry photoresist film; and

patterning the dry photoresist film to form a plurality of openings in the dry photoresist film to expose a top surface of each of the LED dies, the patterned dry photoresist film being substantially above the plurality of LED dies;

depositing a phosphor-containing material only on the exposed top surface of each the LED dies; and

removing the patterned dry photoresist film.

2. The method of claim 1, wherein the patterned dry photoresist film is configured to cover bond pad areas on the LED dies.

3. The method of claim 1, wherein a thickness of the photoresist layer is equal to a desired thickness of the phosphor-containing material.

4. The method of claim 1, wherein depositing the phosphor-containing material in each of the openings in the patterned dry resist film comprises:

depositing the phosphor-containing material on the patterned photoresist layer and the LED dies; and

removing the phosphor-containing material from the top surface of the photoresist layer and on the top surface of the LED dies that protrudes above the top surface of the stencil.

5. The method of claim 1, wherein depositing the phosphor-containing material in each of the openings in the photoresist layer comprises using a screen printing method.

6. The method of claim 1, wherein the plurality of LEDs is formed on a semiconductor substrate.

7. The method of claim 1, wherein the plurality of LEDs is formed on a silicon wafer.

8. The method of claim 1, wherein the plurality of LEDs is formed on a silicon carbide (SiC) substrate.

9. The method of claim 1, wherein the plurality of LEDs is formed on a Sapphire (Al₂O₃) substrate.

10. A method for depositing a layer of phosphor-containing material on a plurality of LED (light-emitting diode) dies on a substrate, the method comprising:

forming a patterned photoresist layer over a plurality of LED dies on a substrate, the patterned photoresist layer having a plurality of openings configured to expose a top surface of each of the LED dies, the patterned photoresist layer being substantially above the plurality of LED dies;

depositing a phosphor-containing material only on the exposed top surface of each the LED dies; and

removing the photoresist layer.

11. The method of claim 10, wherein forming the photoresist layer comprising:

disposing a layer of dry photoresist film over the template;

disposing a mask layer over the dry photoresist film; and

forming a plurality of openings in the dry photoresist film.

12. The method of claim 10, wherein depositing the phosphor-containing material in each of the openings in the photoresist layer comprises using a screen printing method.

13. The method of claim 10, wherein the plurality of LEDs is formed on a semiconductor substrate.

14. The method of claim 10, wherein the plurality of LEDs is formed on a silicon wafer.

15. A method for depositing a layer of phosphor-containing material on a plurality of LED (light-emitting diode) dies on a substrate, the method comprising:

forming a template over a plurality of LED dies on a substrate, the template having a plurality of openings configured to expose a top surface of each of the LED dies, a bottom surface of the template being substantially aligned to top surfaces of the LED dies;

depositing a phosphor-containing material only on the exposed top surface of each the LED dies; and

removing the template.

16. The method of claim 15, wherein the template is made of a material that can be selectively etched from the phosphor-containing material.

17. The method of claim 15, wherein the template has a non-sticky surface such that the template can be removed from the deposited phosphor-containing material.

18. The method of claim 15, wherein the template is a patterned dry photoresist film.

19. The method of claim 15, wherein the plurality of LEDs is formed on a semiconductor substrate.

20. The method of claim 15, wherein the plurality of LEDs is formed on a silicon wafer.