Copper Bonding Wire, Method for Manufacturing Copper Bonding Wire, and Semiconductor Device

A method for manufacturing a copper bonding wire made of a copper alloy having a copper purity of 99.99 mass % or more, the method comprising:

• preparing a copper wire made of a copper alloy having a copper purity of 99.99 mass % or more;
• drawing the copper wire;
• and
• performing a final heat treatment on the drawn copper wire to produce the copper bonding wire, the copper bonding wire being configured such that:
• a density of crystal grain boundary in a cross section perpendicular to a wire axis of the copper bonding wire is 0.01 μm−1 or more and less than 0.6 μm−1;
• among crystal orientations in a wire axis direction in the cross section, a value obtained by dividing an orientation ratio of a crystal orientation <111> having an angular difference of 15° or less relative to the wire axis direction by an orientation ratio of a crystal orientation <101> having an angular difference of 15° or less relative to the wire axis direction is 10 or more and 650 or less;
• a dynamic hardness in the cross section is 45 or more and 90 or less;
• and
• an elastic modulus in the cross section is 20 GPa or more and 70 GPa or less.

A power semiconductor device comprising at least one substrate, at least one semiconductor element on the substrate, an electrode on a surface of the semiconductor element, a semiconductor element upper substrate on the semiconductor element, at least one circuit pattern on the substrate, and

• a copper wire connecting one or more selected from the group consisting of the electrodes on the surface of the semiconductor element, the electrode on the surface of the semiconductor element and an external electrode, the electrode on the surface of the semiconductor element and one of the circuit patterns, the electrode on the surface of the semiconductor element and a terminal, two adjacent circuit patterns among the circuit patterns, one of the circuit patterns and the terminal, the substrates, and the semiconductor element upper substrate and the circuit pattern, wherein:
• the copper wire is a copper bonding wire made of a copper alloy having a copper purity of 99.99 mass % or more;
• and
• the copper bonding wire is configured such that:
• a density of crystal grain boundary in a cross section perpendicular to a wire axis of the copper bonding wire is 0.01 μm−1 or more and less than 0.6 μm−1;
• among crystal orientations in a wire axis direction in the cross section, a value obtained by dividing an orientation ratio of a crystal orientation <111> having an angular difference of 15° or less relative to the wire axis direction by an orientation ratio of a crystal orientation <101> having an angular difference of 15° or less relative to the wire axis direction is 10 or more and 650 or less;
• a dynamic hardness in the cross section is 45 or more and 90 or less;
• and
• an elastic modulus in the cross section of the copper bonding wire is 20 GPa or more and 70 GPa or less.