Copper bonding wire for semiconductor device and bonding structure thereof
View Patent ↗A bonding structure and a copper bonding wire for semiconductor device include a ball-bonded portion formed by bonding to the aluminum electrode a ball formed on a front end of the copper bonding wire. After being heated at any temperature between 130° C. and 200° C., the ball-bonded portion exhibits a relative compound ratio R1 of 40-100%, the relative compound ratio R1 being a ratio of a thickness of a Cu—Al intermetallic compound to thicknesses of intermetallic compounds that are composed of Cu and Al and formed on a cross-sectional surface of the ball-bonded portion.
1. A bonding structure of a copper bonding wire connected to an electrode of a semiconductor device through a ball-bonded portion obtained by bonding to an aluminum electrode a ball portion formed on a front end of said copper bonding wire, wherein said ball-bonded portion exhibits, on a cross-sectional surface thereof, a relative compound ratio R1 of 50-100% after being heated at any temperature in a range of 130-200° C., said relative compound ratio R1 being a ratio of a thickness of an intermetallic compound of a CuAl phase to a total thickness of intermetallic compounds that are composed of Cu and Al and formed on a cross-sectional surface of said ball-bonded portion.
2. The bonding structure according to claim 1 , wherein said ball-bonded portion exhibits, on the cross-sectional surface thereof, a relative compound ratio R2 of 50-100% after being heated at any temperature in the range of 130-200° C. and at any relative humidity in a range of 85-100%, said relative compound ratio R2 being a ratio of the thickness of said intermetallic compound of the CuAl phase to the total thickness of the intermetallic compounds that are composed of Cu and Al and formed on the cross-sectional surface of said ball-bonded portion.
3. The bonding structure according to claim 1 , wherein a ratio of a total thickness of intermetallic compounds of Cu 9 Al 4 and CuAl 2 phases to the total thickness of the intermetallic compounds that are composed of Cu and Al and formed in said ball-bonded portion, is not lower than 0% but lower than 40%.
4. The bonding structure according to claim 1 , wherein said ball-bonded portion includes a concentrated layer of at least one of Pd, Au and Ag serving as electrically-conductive metals.
5. The bonding structure according to claim 4 , wherein said ball-bonded portion further includes an intermetallic compound composed of: Cu; Al; and at least one of Pd, Au and Ag serving as the electrically-conductive metals.
6. The bonding structure according to claim 1 , wherein said ball-bonded portion further includes a Cu alloy layer containing at least one of Pd, Au and Ag serving as electrically-conductive metals in a total concentration of up to 0.5-30 mol %.
7. A copper bonding wire for semiconductor device connected to an electrode of a semiconductor device through a ball-bonded portion obtained by bonding to an aluminum electrode a ball portion formed on a front end of said copper bonding wire, wherein said ball-bonded portion exhibits, on a cross-sectional surface thereof, a relative compound ratio R1 of 50-100% after being heated at any temperature in a range of 130-200° C., said relative compound ratio R1 being a ratio of a thickness of an intermetallic compound of a CuAl phase to a total thickness of intermetallic compounds that are composed of Cu and Al and formed on a cross-sectional surface of said ball-bonded portion.
8. The copper bonding wire for semiconductor device according to claim 7 , comprising:
a core member mainly composed of copper; and
an outer layer mainly composed of at least one of Pd, Au and Ag serving as electrically-conductive metals.
9. The copper bonding wire for semiconductor device according to claim 8 , wherein said outer layer includes:
a single metal outer layer composed of one of Pd, Au and Ag serving as the electrically-conductive metals; and
an alloy outer layer mainly composed of at least two of Pd, Au and Ag serving as the electrically-conductive metals.
10. The copper bonding wire for semiconductor device according to claim 9 , wherein said outer layer is formed to a thickness of 0.01-0.4 μm.
11. The copper bonding wire for semiconductor device according to claim 7 , containing at least one of Pd, Au and Ag serving as the electrically-conductive metals in a range of 0.1-3 mol %.
12. The copper bonding wire for semiconductor device according to claim 8 , containing at least one of P, Si, B and Ge, in a range of 0.0001-0.03 mol %.
13. The bonding structure according to claim 2 , wherein a ratio of a total thickness of intermetallic compounds of Cu 9 Al 4 and CuAl 2 phases to the total thickness of the intermetallic compounds that are composed of Cu and Al and formed in said ball-bonded portion, is not lower than 0% but lower than 40%.
14. The copper bonding wire for semiconductor device according to claim 8 , containing at least one of Pd, Au and Ag serving as the electrically-conductive metals in a range of 0.1-3 mol %.