Chromium/titanium/aluminum-based semiconductor device contact fabrication

Patent metadata

Field	Value
Publication number	US-9514947-B2
Application number	US-201514747150-A
Country	US
Kind code	B2
Filing date	Jun 23, 2015
Priority date	Jun 25, 2007
Publication date	Dec 6, 2016
Grant date	Dec 6, 2016

Abstract

A contact to a semiconductor including sequential layers of Cr, Ti, and Al is provided, which can result in a contact with one or more advantages over Ti/Al-based and Cr/Al-based contacts. For example, the contact can: reduce a contact resistance; provide an improved surface morphology; provide a better contact linearity; and/or require a lower annealing temperature, as compared to the prior art Ti/Al-based contacts.

First claim

What is claimed is:

1. A method comprising:
forming an ohmic contact to a group III nitride layer in a semiconductor structure, the group III nitride layer having an Aluminum molar fraction of at least approximately 0.5, wherein the forming includes:
forming a multi-layer structure comprising:
the semiconductor structure;
a Chromium layer over the semiconductor structure;
a Titanium layer directly on the Chromium layer; and
an Aluminum layer directly on the Titanium layer; and

annealing the multi-layer structure.

2. The method of claim 1 , the multi-layer structure further comprising a barrier layer directly on the Aluminum layer.

3. The method of claim 2 , wherein the barrier layer is a Titanium layer.

4. The method of claim 2 , the multi-layer structure further comprising a Gold layer directly on the barrier layer.

5. The method of claim 4 , wherein at least one layer in the multi-layer structure is discontinuous.

6. The method of claim 5 , wherein the at least one layer includes the Chromium layer.

7. The method of claim 1 , the multi-layer structure further comprising:
a buffer layer directly on the Aluminum layer;
a barrier layer directly on the buffer layer; and
a surface protective layer directly on the barrier layer.

8. The method of claim 7 , wherein the barrier layer includes at least one of: Titanium, Chromium, Nickel, Cobalt, Platinum, Lead, Molybdenum, or Tungsten.

9. The method of claim 1 , wherein the annealing is performed at a temperature between approximately 850 degrees Celsius and approximately 1100 degrees Celsius.

10. A method of fabricating a semiconductor device comprising:
forming an ohmic contact on a semiconductor structure of the semiconductor device, wherein the forming includes:
forming a multi-layer structure comprising:
the semiconductor structure;
a Chromium layer over the semiconductor structure;
a Titanium layer directly on the Chromium layer; and
an Aluminum layer directly on the Titanium layer; and

annealing the multi-layer structure at a temperature between approximately 850 degrees Celsius and approximately 1100 degrees Celsius.

11. The method of claim 10 , wherein at least one layer in the multi-layer structure is discontinuous.

12. The method of claim 11 , wherein the at least one layer includes the Chromium layer, and wherein the method further comprises depositing a second metal, distinct from the Chromium in a set of openings of the Chromium layer.

13. The method of claim 12 , wherein the second metal has at least one of: improved adhesive properties or improved reflective properties than the Chromium layer.

14. The method of claim 10 , wherein the forming the multi-layer structure further includes forming a Titanium layer directly on the Aluminum layer.

15. The method of claim 10 , wherein the ohmic contact is to a group III nitride layer in the semiconductor structure, and wherein the group III nitride layer has an Aluminum molar fraction of at least approximately 0.5.

16. The method of claim 10 , wherein the device is one of: a light emitting diode, a laser, a field effect transistor, a solar cell, a charge coupled device, a Schottky diode, or a p-n junction diode.

17. A method of fabricating a light emitting device, the method comprising:
forming an ohmic contact to a group III nitride layer in a semiconductor structure of the light emitting device, the group III nitride layer having an Aluminum molar fraction of at least approximately 0.5, wherein the forming includes:
forming a multi-layer structure comprising:
the semiconductor structure;
a Chromium layer over the semiconductor structure;
a Titanium layer directly on the Chromium layer; and
an Aluminum layer directly on the Titanium layer; and

annealing the multi-layer structure.

18. The method of claim 17 , wherein the annealing is performed at a temperature between approximately 850 degrees Celsius and approximately 1100 degrees Celsius.

19. The method of claim 17 , wherein at least one layer in the multi-layer structure is discontinuous.

20. The method of claim 19 , wherein the at least one layer includes the Chromium layer.

Assignees

• Sensor Electronic Tech Inc

Inventors

• Gaska Remigijus
• Hu Xuhong
• Shur Michael
• Gaevski Mikhail

Classifications

• H01S5/3013

  AIIIBV compounds · CPC title

• H10W72/952

  comprising metals or metalloids, e.g. PbSn, Ag or Cu · CPC title

• H10W72/934

  Cross-sectional shape, i.e. in side view · CPC title

• H10W72/923

  Bond pads having multiple stacked layers · CPC title

• H10W72/019

  of bond pads · CPC title