Etching method

A method of etching a ruthenium film, comprising:

• a first step of etching the ruthenium film by plasma processing using oxygen-containing gas;
• a second step of etching the ruthenium film by plasma processing using chlorine-containing gas;
• and
• acquiring in-plane distribution data of a thickness of the ruthenium film,
• wherein the first step and the second step are performed alternately, and
• in the first step,
• a surface of the ruthenium film is etched due to a generation of a volatile oxide of ruthenium and, at the same time, a non-volatile oxide of ruthenium is generated on the surface of the ruthenium film,
• in the second step,
• the surface of the ruthenium film is etched due to a removal of the non-volatile oxide and, at the same time, a non-volatile chloride of ruthenium is generated on the surface of the ruthenium film,
• in the first step after the second step, the surface of the ruthenium film is etched due to a removal of the non-volatile chloride and the generation of the volatile oxide and, at the same time, the non-volatile oxide is generated, and
• in the first step and the second step, in-plane temperature distribution of the ruthenium film is controlled based on the in-plane distribution data of the thickness.