Ruthenium-etching solution, method for manufacturing ruthenium-etching solution, method for processing object to be processed, and method for manufacturing ruthenium-containing wiring

A ruthenium-etching solution for carrying out an etching process on ruthenium, the ruthenium-etching solution comprising:

• orthoperiodic acid;
• and
• ammonia as the sole pH adjuster,
• wherein a pH is more than 8 and 9.5 or lower,
• the content of orthoperiodic acid is 0.5 to 3% by mass, and
• a number of particles larger than 100 nm contained in the etching solution is 20 particles/ml or less, and
• the ruthenium etching solution comprises no slurry and no abrasive,
• wherein the ruthenium-etching solution is manufactured by a method consisting of:
• dissolving orthoperiodic acid in water to obtain an orthoperiodic acid solution,
• mixing the orthoperiodic acid solution with aqueous ammonia to adjust the pH of the mixed solution to more than 8 and 9.5 or lower, and
• filtering the mixed solution with a filter.