SOLID STATE LIGHTING DEVICES WITH IMPROVED CONTACTS AND ASSOCIATED METHODS OF MANUFACTURING

• US 20120049756A1
• Filed: 08/31/2010
• Published: 03/01/2012
• Est. Priority Date: 08/31/2010
• Status: Active Grant

• Current Assignee: Micron Technology, Inc.
• Original Assignee: Micron Technology, Inc.
• Inventors: Schubert, Martin F.
• Granted Patent: US 8,664,684 B2
• Time in Patent Office: Days
• US Class Current: 315/291
• 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 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H01L 2933/0016 relating to electrodes
• CPC Class Codes: H01L 2933/0025 relating to coatings
• CPC Class Codes: H01L 2933/0066 relating to arrangements for conducting electric current to or from the semiconductor body
• CPC Class Codes: H01L 33/06 within the light emitting region, e.g. quantum confinement structure or tunnel barrier
• CPC Class Codes: H01L 33/10 with a light reflecting structure, e.g. semiconductor Bragg reflector
• CPC Class Codes: H01L 33/14 with a carrier transport control structure, e.g. highly-doped semiconductor layer or current-blocking structure
• CPC Class Codes: H01L 33/32 containing nitrogen
• CPC Class Codes: H01L 33/36 characterised by the electrodes
• CPC Class Codes: H01L 33/38 with a particular shape
• CPC Class Codes: H01L 33/382 the electrode extending partially in or entirely through the semiconductor body
• CPC Class Codes: H01L 33/385 the electrode extending at least partially onto a side surface of the semiconductor body
• CPC Class Codes: H01L 33/387 with a plurality of electrode regions in direct contact with the semiconductor body and being electrically interconnected by another electrode layer
• CPC Class Codes: H01L 33/40 Materials therefor
• CPC Class Codes: H01L 33/405 Reflective materials
• CPC Class Codes: H01L 33/42 Transparent materials
• CPC Class Codes: H01L 33/44 characterised by the coatings, e.g. passivation layer or anti-reflective coating
• CPC Class Codes: H01L 33/46 Reflective coating, e.g. dielectric Bragg reflector
• CPC Class Codes: H01L 33/60 Reflective elements
• CPC Class Codes: H01L 33/62 : Arrangements for conducting electric current to or from the semiconductor body, e.g. lead-frames, wire-bonds or solder balls
• CPC Class Codes: H10K 50/814 : combined with auxiliary electrodes, e.g. ITO layer combined with metal lines

Abstract

Solid state lighting (“SSL”) devices with improved contacts and associated methods of manufacturing are disclosed herein. In one embodiment, an SSL device includes an SSL structure having a first semiconductor material, a second semiconductor material spaced apart from the first semiconductor material, and an active region between the first and second semiconductor materials. The SSL device also includes a first contact on the first semiconductor material and a second contact on the second semiconductor material, where the first and second contacts define the current flow path through the SSL structure. The first or second contact is configured to provide a current density profile in the SSL structure based on a target current density profile.

Claims

1. A solid state lighting (“

SSL”

) device, comprising;

a first semiconductor material;

a second semiconductor material spaced apart from the first semiconductor material;

an active region between the first and second semiconductor materials; and

a contact on the first or second semiconductor material;

wherein the contact includes a first material having a first contact resistance and a second material having a second contact resistance, the first contact resistance being different from the second contact resistance; and

wherein at least one of a shape, a size, a profile, and a distribution of the first and second materials varies from one region of the SSL device to another region of the SSL device.

2. The SSL device of claim 1 wherein:

the contact is a first contact on the first semiconductor material;

the SSL device further includes a second contact on the second semiconductor material;

the second contact is laterally spaced apart from the first contact;

the first semiconductor material includes a P-type gallium nitride (“

GaN”

) material;

the second semiconductor material includes an N-type GaN material;

the active region includes at least one of a bulk indium gallium nitride (“

InGaN”

) material, an InGaN single quantum well (“

SQW”

), and GaN/InGaN multiple quantum wells (“

MQWs”

);

the first material includes an insulative material on the first semiconductor material, the insulative material having a plurality of openings extending between the first semiconductor material and a surface of the insulative material, at least one of the plurality of openings having a different shape or size from the other openings;

the second material includes a conductive material on the insulative material, the conductive material having a first portion on the surface of the insulative material and a second portion in the openings of the insulative material;

the insulative material includes a first region and a second region spaced apart from the first region;

the first region includes a first number of the openings;

the second region includes a second number of the openings; and

the first number is different than the second number of openings.

3. The SSL device of claim 1 wherein:

the contact is a first contact on the first semiconductor material;

the SSL device further includes a second contact on the second semiconductor material;

the second contact is laterally spaced apart from the first contact;

the first semiconductor material includes a P-type gallium nitride (GaN) material;

the second semiconductor material includes an N-type GaN material;

the active region includes at least one of a bulk indium gallium nitride (InGaN) material, an InGaN single quantum well (“

SQW”

), and GaN/InGaN multiple quantum wells (“

MQWs”

);

the first material includes an insulative material on the first semiconductor material, the insulative material having a plurality of openings extending between the first semiconductor material and a surface of the insulative material;

the second material includes a conductive material on the insulative material, the conductive material having a first portion on the surface of the insulative material and a second portion in the openings of the insulative material;

the insulative material includes a first region and a second region spaced apart from the first region;

the first region includes a first number of the openings;

the second region includes a second number of the openings; and

the first number is different from the second number of openings.

4. The SSL device of claim 1 wherein:

the contact is a first contact on the first semiconductor material;

the SSL device further includes a second contact on the second semiconductor material;

the second contact is laterally spaced apart from the first contact;

the first semiconductor material includes a P-type gallium nitride (GaN) material;

the second semiconductor material includes an N-type GaN material;

the active region includes at least one of a bulk indium gallium nitride (InGaN) material, an InGaN single quantum well (“

SQW”

), and GaN/InGaN multiple quantum wells (“

MQWs”

);

the first material includes an insulative material on the first semiconductor material, the insulative material having a plurality of openings extending between the first semiconductor material and a surface of the insulative material; and

the second material includes a conductive material on the insulative material, the conductive material having a first portion on the surface of the insulative material and a second portion in the openings of the insulative material.

5. The SSL device of claim 1 wherein:

the first material includes an insulative material on the first semiconductor material, the insulative material having a plurality of openings extending between the first semiconductor material and a surface of the insulative material; and

the second material includes a conductive material on the insulative material, the conductive material having a first portion on the surface of the insulative material and a second portion in the openings of the insulative material.

6. The SSL device of claim 1 wherein:

the first material includes an insulative material on the first semiconductor material, the insulative material having a plurality of openings extending between the first semiconductor material and a surface of the insulative material;

the second material includes a conductive material on the insulative material, the conductive material having a first portion on the surface of the insulative material and a second portion in the openings of the insulative material; and

at least one of the plurality of openings has a different shape or size from the other openings.

7. The SSL device of claim 1 wherein:

the contact is a first contact on the first semiconductor material;

the SSL device further includes a second contact on the second semiconductor material;

the second contact is laterally spaced apart from the first contact;

the first semiconductor material includes a P-type gallium nitride (“

GaN”

) material;

the second semiconductor material includes an N-type GaN material;

the active region includes at least one of a bulk indium gallium nitride (“

InGaN”

) material, an InGaN single quantum well (“

SQW”

), and GaN/InGaN multiple quantum wells (“

MQWs”

);

the first material includes a conductive material on the first semiconductor material, the conductive material having a plurality of openings extending between the first semiconductor material and the conductive material, at least one of the plurality of openings having a different shape or size from the other openings;

the conductive material includes at least one of aluminum zinc oxide and fluorine-doped tin oxide;

the second material includes a contact material in the openings of the conductive material; and

the contact material includes at least one of copper (Cu), aluminum (Al), silver (Ag), gold (Au), platinum (Pt).

8. The SSL device of claim 1 wherein:

the first material includes a conductive material on the first semiconductor material, the conductive material having a plurality of openings extending between the first semiconductor material and the conductive material, the conductive material having the first contact resistance, and at least one of the plurality of openings having a different shape or size from the other openings;

the second material includes a contact material in the openings of the conductive material, the contact material having the second contact resistance; and

the second contact resistance is greater than the first contact resistance.

9. The SSL device of claim 1 wherein:

the first material includes a conductive material on the first semiconductor material, the conductive material having a plurality of openings extending between the first semiconductor material and the conductive material;

the second material includes a contact material in the openings of the conductive material, the contact material having the second contact resistance; and

the second contact resistance is greater than the first contact resistance.

10. The SSL device of claim 1, further comprising:

an insulative material between the first semiconductor material and the active region or between the active region and the second semiconductor material;

the insulative material having a plurality of openings, at least one of the plurality of openings having a different shape or size from the other openings; and

a conductive material in the plurality of openings.

11. The SSL device of claim 1 wherein:

the contact is a first contact on the first semiconductor material;

the SSL device further includes a second contact on the second semiconductor material;

the second contact is opposite the first contact;

the first material includes a conductive material on the first semiconductor material;

the second material includes an insulative material; and

the insulative material includes a plurality of insulative portions having different electrical conductivities.

12. The SSL device of claim 1 wherein:

the contact is a first contact on the first semiconductor material;

the SSL device further includes a second contact on the second semiconductor material;

the second contact is opposite the first contact;

the second contact includes a contact finger on the second semiconductor material;

the first material includes a conductive material on the first semiconductor material;

the second material includes an insulative material;

the insulative material includes a first insulative portion generally aligned with the contact finger and a second insulative portion adjacent to the first insulative portion; and

the first insulative portion has a higher contact resistance than the second insulative portion.

13. The SSL device of claim 1 wherein:

the contact is a first contact on the first semiconductor material;

the SSL device further includes a second contact on the second semiconductor material;

the second contact is opposite the first contact;

the second contact includes a contact finger on the second semiconductor material;

the first material includes a conductive material on the first semiconductor material;

the second material includes a contact material generally encapsulated by the conductive material; and

the contact material has a lower contact resistance than the conductive material.

14. The SSL device of claim 1 wherein:

the contact is a first contact on the first semiconductor material;

the SSL device further includes a second contact on the second semiconductor material;

the second contact is opposite the first contact;

the second contact includes a contact finger on the second semiconductor material;

the first material includes a conductive material on the first semiconductor material;

the second material includes a contact material generally encapsulated by the conductive material;

the contact material includes silver (Ag); and

the conductive material includes aluminum (Al).

15. The SSL device of claim 1 wherein:

the contact is a first contact on the first semiconductor material;

the SSL device further includes;

an aperture extending from a surface of the first contact into the second semiconductor material via the first semiconductor material and the active region, the aperture having a first end proximate the surface of the first contact, a second end opposite the first end, and a side wall between the first and second ends; and

an isolation material on the side wall of the aperture and the surface of the first contact;

the SSL device further includes a second contact in the aperture;

the first material of the first contact includes a conductive material spaced apart from the aperture; and

the second material of the first contact includes an insulative material between the aperture and the conductive material.

16. The SSL device of claim 1 wherein:

the contact is a first contact on the first semiconductor material;

the SSL device further includes;

an aperture extending from a surface of the first contact into the second semiconductor material via the first semiconductor material and the active region, the aperture having a first end proximate the surface of the first contact, a second end opposite the first end, and a side wall between the first and second ends; and

an isolation material on the side wall of the aperture and the surface of the first contact;

the SSL device further includes a second contact in the aperture;

the first material of the first contact includes a conductive material adjacent to the aperture;

the second material of the first contact includes a contact material spaced apart from the aperture and between the first semiconductor material and the conductive material; and

the contact material has a lower contact resistance than the conductive material.

17. A solid state lighting (“

SSL”

) device, comprising;

an SSL structure having a first semiconductor material, a second semiconductor material spaced apart from the first semiconductor material, and an active region between the first and second semiconductor materials;

a first contact on the first semiconductor material; and

a second contact on the second semiconductor material, the first and second contacts define a current flow path through the SSL structure; and

wherein the first or the second contact is configured to provide defined current flow paths through the first and second semiconductor materials that provide a current density profile in the SSL structure based on a target current density profile.

18. The SSL device of claim 17 wherein the first or second contact includes an insulative material configured to impede a current flow through a region of the SSL structure.

19. The SSL device of claim 17 wherein the first or second contact includes a contact material configured to increase a current conductance through a region of the SSL structure.

20. The SSL device of claim 17 wherein:

the first or second contact includes a first material and a second material;

the first material has a plurality of openings holding at least a portion of the second material; and

at least one of the openings has a shape, a size, or a profile that is different from the other openings.

21. The SSL device of claim 17 wherein:

the first or second contact includes an insulative material and a conducive material;

the insulative material has a plurality of openings holding at least a portion of the conductive material; and

at least one of the openings has a shape, a size, or a profile that is different from the other openings.

22. The SSL device of claim 17 wherein:

the first or second contact includes a conductive material and a contact material;

the contact material has a higher electrical conductance than the conductive material;

the conductive material has a plurality of openings holding at least a portion of the contact material; and

at least one of the openings has a shape, a size, or a profile that is different from the other openings.

23. A method of forming a solid state lighting (“

SSL”

) device, comprising;

forming a SSL structure on a substrate material, the SSL structure having a first semiconductor material, a second semiconductor material spaced apart from the first semiconductor material, and an active region between the first and second semiconductor materials;

forming a contact on the first or second semiconductor material, the contact including a first material having a first contact resistance and a second material having a second contact resistance, the first contact resistance being different from the second contact resistance; and

wherein at least one of a shape, a size, a profile, and a distribution of the first and/or second materials varies from one region of the SSL structure to another region of the SSL structure based on a target current density profile in the SSL structure.

24. The method of claim 23 wherein:

the first material includes an insulative material on the first semiconductor material, the insulative material having a plurality of openings extending between the first semiconductor material and a surface of the insulative material;

the second material includes a conductive material on the insulative material, the conductive material having a first portion on the surface of the insulative material and a second portion in the openings of the insulative material; and

adjusting at least one of the shape, the size, the profile, and the distribution of the first and/or second materials includes adjusting at least one of a shape, a size, a profile, and a distribution of the openings based on the target current density profile in the SSL structure.

25. The method of claim 23 wherein:

the first material includes a conductive material on the first semiconductor material, the conductive material having a plurality of openings extending between the first semiconductor material and the conductive material;

the second material includes a contact material in the openings of the conductive material, the contact material having a lower contact resistance than the conductive material; and

adjusting at least one of the shape, the size, the profile, and the distribution of the first and/or second materials includes adjusting at least one of a shape, a size, a profile, and a distribution of the openings based on the target current density profile in the SSL structure.

26. The method of claim 23 wherein:

the contact is a first contact on the first semiconductor material;

the SSL device further includes a second contact on the second semiconductor material;

the second contact is opposite the first contact;

the second contact includes a contact finger on the second semiconductor material;

the first material includes a conductive material on the first semiconductor material;

the conductive material includes a plurality of openings extending from the first semiconductor material into the conductive material, the openings being generally offset from the contact finger of the second contact;

the second material includes a contact material in the plurality of openings of the conductive material; and

adjusting at least one of the shape, the size, the profile, and the distribution of the first and/or second materials includes adjusting at least one of a shape, a size, a profile, and a distribution of the openings based on the target current density profile in the SSL structure.

27. The method of claim 23 wherein:

the contact is a first contact on the first semiconductor material;

the SSL device further includes;

an aperture extending from a surface of the first contact into the second semiconductor material via the first semiconductor material and the active region, the aperture having a first end proximate the surface of the first contact, a second end opposite the first end, and a side wall between the first and second ends; and

an isolation material on the side wall of the aperture and the surface of the first contact;

the SSL device further includes a second contact in the aperture;

the first material of the first contact includes a conductive material spaced apart from the aperture;

the second material of the first contact includes an insulative material between the aperture and the conductive material; and

adjusting at least one of the shape, the size, the profile, and the distribution of the first and/or second materials includes adjusting at least one of a shape, a size, a profile, and a distribution of the openings based on the target current density profile in the SSL structure.

28. The method of claim 23 wherein:

the contact is a first contact on the first semiconductor material;

the SSL device further includes;

an aperture extending from a surface of the first contact into the second semiconductor material via the first semiconductor material and the active region, the aperture having a first end proximate the surface of the first contact, a second end opposite the first end, and a side wall between the first and second ends; and

an isolation material on the side wall of the aperture and the surface of the first contact;

the SSL device further includes a second contact in the aperture;

the first material of the first contact includes a conductive material adjacent to the aperture;

the second material of the first contact includes a contact material spaced apart from the aperture and between the first semiconductor material and the conductive material; and

adjusting at least one of the shape, the size, the profile, and the distribution of the first and/or second materials includes adjusting at least one of a shape, a size, a profile, and a distribution of the contact material based on the target current density profile in the SSL structure

29. A method of operating a solid state lighting (“

SSL”

) device, comprising;

applying an electrical voltage between a first contact and a second contact on a SSL structure, the SSL structure having a first semiconductor material, a second semiconductor material spaced apart from the first semiconductor material, and an active region between the first and second semiconductor materials, at least one of the first and second contacts including a first material having a first contact resistance and a second material having a second contact resistance, the first contact resistance being different from the second contact resistance; and

providing a regional current density in the SSL structure with the first and second materials based on a target current density profile.

30. The method of claim 29 wherein:

the first material includes an insulative material on the first semiconductor material, the insulative material having a plurality of openings extending between the first semiconductor material and a surface of the insulative material;

the second material includes a conductive material on the insulative material, the conductive material having a first portion on the surface of the insulative material and a second portion in the openings of the insulative material; and

providing the regional current density includes impeding a current flow using the insulative material.

31. The method of claim 29 wherein:

the first material includes a conductive material on the first semiconductor material, the conductive material having a plurality of openings extending between the first semiconductor material and the conductive material;

the second material includes a contact material in the openings of the conductive material, the contact material having a lower contact resistance than the conductive material; and

providing the regional current density includes increasing a current flow using the contact material.

32. The method of claim 29 wherein:

the second contact is opposite the first contact;

the second contact includes a contact finger on the second semiconductor material;

the first material includes a conductive material on the first semiconductor material;

the second material includes an insulative material;

the insulative material including a first insulative portion generally aligned with the contact finger and a second insulative portion adjacent to the first insulative portion; and

providing the regional current density includes impeding a current flow with the first insulative portion in a region generally aligned with the contact finger.

33. The method of claim 29 wherein:

the second contact is opposite the first contact;

the second contact includes a contact finger on the second semiconductor material;

the first material includes a conductive material on the first semiconductor material;

the conductive material includes a plurality of openings extending from the first semiconductor material into the conductive material, the openings being generally offset from the contact finger of the second contact;

the second material includes a contact material in the plurality of openings of the conductive material; and

providing the regional current density includes increasing a current flow with the contact material in a region generally offset from the contact finger.

34. The method of claim 29 wherein:

the SSL device further includes;

an aperture extending from a surface of the first contact into the second semiconductor material via the first semiconductor material and the active region, the aperture having a first end proximate the surface of the first contact, a second end opposite the first end, and a side wall between the first and second ends; and

an isolation material on the side wall of the aperture and the surface of the first contact;

the second contact is in the aperture;

the first material of the first contact includes a conductive material spaced apart from the aperture;

the second material of the first contact includes an insulative material between the aperture and the conductive material; and

providing the regional current density includes impeding a current flow with the insulative material in a region adjacent to the aperture.

35. The method of claim 29 wherein:

the SSL device further includes;

an aperture extending from a surface of the first contact into the second semiconductor material via the first semiconductor material and the active region, the aperture having a first end proximate the surface of the first contact, a second end opposite the first end, and a side wall between the first and second ends; and

an isolation material on the side wall of the aperture and the surface of the first contact;

the second contact is in the aperture;

the first material of the first contact includes a conductive material adjacent to the aperture;

the second material of the first contact includes a contact material spaced apart from the aperture and between the first semiconductor material and the conductive material; and

providing the regional current density includes increasing a current flow with the contact material in a region generally offset from the aperture.