IP Library Granted Patent US 12,588,521
Granted Patent B2
US 12,588,521 · App. 18/169,518 · Granted Mar 24, 2026

Metal nitride core-shell particle die-attach material

Inventors: Afshin Dadvand (Durham, NC); Devarajan Balaraman (Apex, NC)
Assignee: Wolfspeed, Inc.
H01L24/29H01L23/49582H01L24/32H01L24/48H01L2224/2979H01L2224/29847H01L2224/29987H01L2224/32245H01L2224/48245H01L2924/182
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Quick Facts
Patent No.
US 12,588,521
App. No.
18/169,518
Granted
Mar 24, 2026
Kind
B2
Abstract

Die attach materials are provided. In one example, the die-attach material includes a plurality of core-shell particles. Each core-shell particle includes a core and a shell on the core. The core includes a conducting material. The shell includes a metal nitride.

Claims (28)

1 . A die-attach material, comprising:

a plurality of core-shell particles, each core-shell particle comprising a core and a shell on the core;

wherein the core comprises a conducting material; and

wherein the shell comprises a copper nitride.

2 . The die-attach material of claim 1 , wherein the metal copper nitride reduces oxidation of the core.

3 . The die-attach material of claim 1 , wherein the die-attach material is an ink.

4 . The die-attach material of claim 1 , wherein the die-attach material is a paste.

5 . The die-attach material of claim 1 , wherein the metal copper nitride decomposes into a metal and a nitrogen gas during bonding of the die-attach material.

6 . The die-attach material of claim 1 , wherein the conducting material of the core comprises copper.

7 . The die-attach material of claim 1 , wherein the plurality of core-shell particles are dispersed in a solution.

8 . The die-attach material of claim 7 , wherein the solution comprises ethylene glycol.

9 . The die-attach material of claim 1 , wherein the plurality of core-shell particles are grafted to a polymer matrix.

10 . The die-attach material of claim 1 , wherein the core has a size of about 1 μm or less.

11 . The die-attach material of claim 1 , wherein the core has a size of in a range of about 1 μm to about 50 μm.

12 . The die-attach material of claim 1 , wherein the shell has a thickness in a range of about 50 nm to about 100 nm.

13 . A die-attach material, comprising:

a plurality of core-shell particles, each core-shell particle comprising a core and a shell on the core;

wherein the core comprises copper and the shell comprises copper nitride; and

wherein the die-attach material is an ink or a paste.

14 . A device, comprising:

a semiconductor die comprising a wide band gap semiconductor material;

a substrate; and

a die-attach material between the semiconductor die and the substrate, the die-attach material comprising a plurality of bonded conductive particles and a metal nitride.

15 . The device of claim 14 , wherein the plurality of bonded conductive particles comprise a plurality of bonded copper particles.

16 . The device of claim 14 , wherein the metal nitride comprises a copper nitride.

17 . The device of claim 14 , wherein the semiconductor die comprises silicon carbide.

18 . The device of claim 14 , wherein the semiconductor die comprises a Group III-nitride.

19 . The device of claim 14 , wherein the metal nitride is interspersed between the plurality of bonded conductive particles.

Assignments (8)
NOTICE OF GRANT OF SECURITY INTEREST IN INTELLECTUAL PROPERTY Recorded Mar 26, 2026
From: WOLFSPEED, INC.
To: U.S. BANK TRUST COMPANY, NATIONAL ASSOCIATION, AS COLLATERAL AGENT
Reel/Frame 075280/0919 →
RELEASE OF SECURITY INTEREST IN INTELLECTUAL PROPERTY COLLATERAL AT REEL/FRAME NO. 64185/0755 Recorded Sep 30, 2025
From: U.S. BANK TRUST COMPANY, NATIONAL ASSOCIATION, AS COLLATERAL AGENT
To: WOLFSPEED, INC.
Reel/Frame 072989/0001 →
NOTICE OF GRANT OF SECURITY INTEREST IN INTELLECTUAL PROPERTY Recorded Sep 30, 2025
From: WOLFSPEED, INC.
To: U.S. BANK TRUST COMPANY, NATIONAL ASSOCIATION, AS COLLATERAL AGENT
Reel/Frame 072992/0113 →
NOTICE OF GRANT OF SECURITY INTEREST IN INTELLECTUAL PROPERTY Recorded Sep 30, 2025
From: WOLFSPEED, INC.
To: U.S. BANK TRUST COMPANY, NATIONAL ASSOCIATION, AS COLLATERAL AGENT
Reel/Frame 072992/0381 →
NOTICE OF GRANT OF SECURITY INTEREST IN INTELLECTUAL PROPERTY Recorded Sep 30, 2025
From: WOLFSPEED, INC.
To: U.S. BANK TRUST COMPANY, NATIONAL ASSOCIATION, AS COLLATERAL AGENT
Reel/Frame 072992/0467 →
NOTICE OF GRANT OF SECURITY INTEREST IN INTELLECTUAL PROPERTY Recorded Sep 30, 2025
From: WOLFSPEED, INC.
To: U.S. BANK TRUST COMPANY, NATIONAL ASSOCIATION, AS COLLATERAL AGENT
Reel/Frame 072992/0588 →
SECURITY INTEREST Recorded Jun 30, 2023
From: WOLFSPEED, INC.
To: U.S. BANK TRUST COMPANY, NATIONAL ASSOCIATION
Reel/Frame 064185/0755 →
ASSIGNMENT OF ASSIGNOR'S INTEREST Recorded May 18, 2023
From: DADVAND, AFSHIN; BALARAMAN, DEVARAJAN
To: WOLFSPEED, INC.
Reel/Frame 063679/0203 →