Bonding wire for semiconductor devices

Patent metadata

Field	Value
Publication number	US-12581982-B2
Application number	US-202117913365-A
Country	US
Kind code	B2
Filing date	Mar 18, 2021
Priority date	Mar 25, 2020
Publication date	Mar 17, 2026
Grant date	Mar 17, 2026

Abstract

There is provided a bonding wire for semiconductor devices that exhibits a favorable bondability even when being applied to wedge bonding at the room temperature, and also achieves an excellent bond reliability. The bonding wire includes a core material of Cu or Cu alloy (hereinafter referred to as a “Cu core material”), and a coating containing a noble metal formed on a surface of the Cu core material. A concentration of Cu at a surface of the wire is 30 to 80 at %.

First claim

The invention claimed is:

1 . A bonding wire for semiconductor devices, the bonding wire comprising:
a core material of Cu or Cu alloy (hereinafter referred to as a “Cu core material”); and a coating containing a noble metal formed on a surface of the Cu core material (hereinafter referred to as a “noble metal coating”), wherein a concentration of Cu at a surface of the wire is more than 50 at % and 80 at % or less.

2 . The bonding wire according to claim 1 , wherein the concentration of Cu at the surface is measured by Auger electron spectroscopy (AES) under the following <Condition>:
<Condition> a center of width of a measuring surface is aligned with a center of width of the wire, the width of the measuring surface is 10% or more and 15% or less of a diameter of the wire, and a length of the measuring surface is five times the width of the measuring surface.

3 . The bonding wire according to claim 1 , wherein the noble metal coating contains Pd.

4 . The bonding wire according to claim 3 , wherein the noble metal coating further contains Au.

5 . The bonding wire according to claim 4 , wherein, in the noble metal coating, a position indicating a maximum concentration of Au is closer to the surface of the wire than a position indicating a maximum concentration of Pd.

6 . The bonding wire according to claim 1 , wherein a maximum concentration of the noble metal in the noble metal coating is 50 at % or more.

7 . The bonding wire according to claim 6 , wherein a maximum concentration of the noble metal in the noble metal coating is determined from a concentration profile in a depth direction that is obtained by performing measurement by Auger electron spectroscopy (AES) under the following <Condition> while digging down the wire from its surface in the depth direction by Ar sputtering:
<Condition> a center of width of a measuring surface is aligned with a center of width of the wire, the width of the measuring surface is 10% or more and 15% or less of a diameter of the wire, and a length of the measuring surface is five times the width of the measuring surface.

8 . The bonding wire according to claim 1 , wherein an average crystal grain size in a cross-section of the Cu core material in a direction perpendicular to a wire axis is 1.4 to 3.2 μm.

9 . The bonding wire according to claim 1 used for wedge-wedge bonding.

10 . A semiconductor device comprising the bonding wire according to claim 1 .

11 . The bonding wire according to claim 1 , wherein the bonding wire satisfies at least one conditions of the following (i) and (ii):
(i) the bonding wire contains at least one element selected from the group consisting of Ni, Zn, Rh, In, Ir and Pt (hereinafter referred to as a “first additive element”), and a concentration of the first additive element in total is 0.1 to 1.5% by mass relative to the entire wire; (ii) the bonding wire contains at least one element selected from the group consisting of P, B, Be, Fe, Mg, Ti, Zn, Ag and Si (hereinafter referred to as a “second additive element”), and a concentration of the second additive element in total is 0.1 to 200 ppm by mass relative to the entire wire.

12 . A method for manufacturing a semiconductor device, the method comprising:
a step of connecting a first electrode on a semiconductor element to a second electrode on a lead frame or circuit board with using the bonding wire according to claim 1 , wherein a first connection between the first electrode and the bonding wire and a second connection between the second electrode and the bonding wire are both performed by wedge bonding.

13 . The method according to claim 12 , wherein the first connection and the second connection are performed at the room temperature.

Assignees

• Nippon Micrometal Corp
• Nippon Steel Chemical & Mat Co Ltd

Inventors

• Eto Motoki
• Oda Daizo
• Uno Tomohiro
• Oyamada Tetsuya

Classifications

• H10W72/07541

  Controlling the environment, e.g. atmosphere composition or temperature · CPC title

• H10W72/5525

  comprising copper [Cu] · CPC title

• H10W72/5522

  comprising gold [Au] · CPC title

• H10W72/5363

  the connected ends being wedge-shaped · CPC title

• H10W72/555

  of outermost layers of multilayered bond wires, e.g. material of a coating · CPC title