Transfer substrate for forming metal wiring and method for forming metal wiring with the transfer substrate

A metal wiring formation method comprising:

• (a) providing a transfer substrate for transferring a metal wiring material to a transfer target, said transfer substrate comprising:
• a substrate;
• at least one metal wiring material formed on the substrate;
• at least one coating layer formed on a surface of the metal wiring material;
• and
• an underlying metal film formed between the substrate and the metal wiring material, wherein the metal wiring material comprises a composition formed by sintering one or more kinds of metal powder having a purity of 99.9 wt % or more and an average particle size of 0.01 μm to 1.0 μm selected from gold powder, silver powder, platinum powder, palladium powder and copper powder;
• the coating layer comprises one or more of any metal of gold, silver, platinum, palladium, ruthenium, rhodium, iridium, chromium, titanium, tungsten, tantalum, nickel, copper and zirconium or an alloy thereof;
• the coating layer comprises a metal or an alloy having a different composition from the composition of the metal wiring material and has a total thickness of 1 μm or less;
• and
• the underlying metal film comprises one or more of any metal of gold, silver, platinum, palladium, ruthenium, rhodium, iridium, chromium, titanium, tungsten, tantalum, nickel, copper and zirconium or an alloy thereof;
• (b) stacking the transfer substrate so as to be opposite to a transfer target;
• (c) heating the transfer substrate and the transfer target;
• and
• (d) pressing the transfer substrate to join and transfer the metal wiring material to the transfer target, wherein a heating temperature of the transfer substrate is set to 80 to 200° C.;
• and a heating temperature of the transfer target is set to 80 to 300° C.,
• wherein a pressure at the time of pressing the transfer substrate is set to 0.1 to 1.5 times the yield strength of the metal wiring material.