To provide a novel Cu bonding wire that achieves a favorable FAB shape and a favorable bondability of the 2nd bonded part, and further achieves favorable bond reliability even in a rigorous high-temperature environment. The bonding wire for semiconductor devices includes: a core material of Cu or Cu alloy; and a coating layer containing conductive metal other than Cu formed on a surface of the core material, wherein the coating layer has a region containing Ni as a main component on a core material side, and has a region containing Au and Ni on a wire surface side, in a thickness direction of the coating layer, a thickness of the coating layer is 10 nm or more and 130 nm or less, a ratio C.sub.Au/C.sub.Ni of a concentration C.sub.Au (mass %) of Au to a concentration C.sub.Ni (mass %) of Ni relative to the entire wire is 0.02 or more and 0.7 or less, a concentration of Au at the surface of the wire is 10 atomic % or more and 90 atomic % or less, and at least one of the following conditions (i) and (ii) is satisfied: (i) a concentration of In relative to the entire wire is 1 ppm by mass or more and 100 ppm by mass or less (ii) a concentration of Ag relative to the entire wire is 1 ppm by mass or more and 500 ppm by mass or less.

There is provided a Cu bonding wire having a Pd coating layer on a surface thereof, that improves bonding reliability of a ball bonded part in a high-temperature and high-humidity environment and is suitable for on-vehicle devices. The bonding wire for a semiconductor device includes a Cu alloy core material and a Pd coating layer formed on a surface of the Cu alloy core material, and the bonding wire contains In of 0.011 to 1.2% by mass and has the Pd coating layer of a thickness of 0.015 to 0.150 m. With this configuration, it is able to increase the bonding longevity of a ball bonded part in a high-temperature and high-humidity environment, and thus to improve the bonding reliability. When the Cu alloy core material contains one or more elements of Pt, Pd, Rh and Ni in an amount, for each element, of 0.05 to 1.2% by mass, it is able to increase the reliability of a ball bonded part in a high-temperature environment of 175 C. or more. When an Au skin layer is further formed on a surface of the Pd coating layer, wedge bondability improves.

There is provided a Cu bonding wire having a Pd coating layer on a surface thereof, that improves bonding reliability of a ball bonded part in a high-temperature and high-humidity environment and is suitable for on-vehicle devices. The bonding wire for a semiconductor device includes a Cu alloy core material and a Pd coating layer formed on a surface of the Cu alloy core material, and the bonding wire contains In of 0.011 to 1.2% by mass and has the Pd coating layer of a thickness of 0.015 to 0.150 m. With this configuration, it is able to increase the bonding longevity of a ball bonded part in a high-temperature and high-humidity environment, and thus to improve the bonding reliability. When the Cu alloy core material contains one or more elements of Pt, Pd, Rh and Ni in an amount, for each element, of 0.05 to 1.2% by mass, it is able to increase the reliability of a ball bonded part in a high-temperature environment of 175 C. or more. When an Au skin layer is further formed on a surface of the Pd coating layer, wedge bondability improves.

A copper-based alloy wire made of a material selected from the group consisting of a copper-gold alloy, a copper-palladium alloy and a copper-gold-palladium alloy is provided. The alloy wire has a polycrystalline structure of a face-centered cubic lattice and consists of a plurality of equi-axial grains. The quantity of grains having annealing twins is 10 percent or more of the total quantity of the grains of the copper-based alloy wire.

A method for treating a bare copper wire and a surface-treated copper wire includes applying a solution including a phosphoric acid-based chelating agent to a surface of a bare copper wire, and drying the copper wire having the solution including the phosphoric acid-based chelating agent attached on the surface thereof.

A bonding wire for a semiconductor device includes a Cu alloy core material and a Pd coating layer formed on a surface thereof. Containing an element that provides bonding reliability in a high-temperature environment improves the bonding reliability of the ball bonded part in high temperature. Furthermore, making an orientation proportion of a crystal orientation <100> angled at 15 degrees or less to a wire longitudinal direction among crystal orientations in the wire longitudinal direction 30% or more when measuring crystal orientations on a cross-section of the core material in a direction perpendicular to a wire axis of the bonding wire, and making an average crystal grain size in the cross-section of the core material in the direction perpendicular to the wire axis of the bonding wire 0.9 to 1.5 m provides a strength ratio of 1.6 or less.

A bonding wire for a semiconductor device, characterized in that the bonding wire includes a Cu alloy core material and a Pd coating layer formed on a surface of the Cu alloy core material, the bonding wire contains an element that provides bonding reliability in a high-temperature environment, and a strength ratio defined by the following Equation (1) is 1.1 to 1.6:

Strength ratio=ultimate strength/0.2% offset yield strength.(1)

A bonding wire for a semiconductor device includes a Cu alloy core material and a Pd coating layer on a surface of the Cu alloy core material, and contains Ga and Ge of 0.011 to 1.2% by mass in total, which is able to increase bonding longevity of the ball bonded part in the high-temperature, high-humidity environment, and thus to improve the bonding reliability. The thickness of the Pd coating layer is preferably 0.015 to 0.150 m. When the bonding wire further contains one or more elements of Ni, Ir, and Pt in an amount, for each element, of 0.011 to 1.2% by mass, it is able to improve the reliability of the ball bonded part in a high-temperature environment at 175 C. or more. When an alloy skin layer containing Au and Pd is further formed on a surface of the Pd coating layer, wedge bondability improves.

A bonding wire for a semiconductor device includes a Cu alloy core material and a Pd coating layer on a surface of the Cu alloy core material, and contains Ga and Ge of 0.011 to 1.2% by mass in total, which is able to increase bonding longevity of the ball bonded part in the high-temperature, high-humidity environment, and thus to improve the bonding reliability. The thickness of the Pd coating layer is preferably 0.015 to 0.150 m. When the bonding wire further contains one or more elements of Ni, Ir, and Pt in an amount, for each element, of 0.011 to 1.2% by mass, it is able to improve the reliability of the ball bonded part in a high-temperature environment at 175 C. or more. When an alloy skin layer containing Au and Pd is further formed on a surface of the Pd coating layer, wedge bondability improves.

A round wire comprising a wire core with a surface, the wire core having a coating layer superimposed on its surface, wherein the wire core itself is a silver-based wire core, wherein the coating layer is a double-layer comprised of a 1 to 100 nm thick inner layer of palladium or nickel and an adjacent 1 to 250 nm thick outer layer of gold, wherein the outer layer of gold exhibits at least one of the following intrinsic properties A1) and A2): A1) the average grain size of the crystal grains in the outer layer of gold, measured in longitudinal direction, is in the range of 0.1 to 0.8 m; A2) 60 to 100% of the crystal grains in the outer layer of gold are oriented in <100> direction, and 0 to 20% of the crystal grains in the outer layer of gold are oriented in <111> direction.