Etching method

A method for selectively etching a first region made of silicon oxide to a second region made of silicon nitride, wherein the second region defines a recess, the first region fills the recess and covers the second region, and a mask is provided above the first region, the method comprising:

• performing a first sequence a plurality of times to etch the first region such that the second region is exposed;
• and
• performing a second sequence once or more to further etch the first region,
• the first sequence includes:
• a first step of generating plasma of a processing gas containing a fluorocarbon gas in a processing container of a plasma processing apparatus to form a fluorocarbon-containing deposit on a workpiece ;
• and
• a second step of etching the first region by radicals of the fluorocarbon contained in the deposit,
• the performing the second sequence once or more is performed on the workpiece processed by the performing the first sequence a plurality of times, and
• the second sequence includes:
• a third step of generating plasma of a processing gas containing a fluorocarbon gas in the processing container to form a fluorocarbon-containing deposit on the workpiece;
• and
• a fourth step of generating plasma of a processing gas containing oxygen gas and an inert gas in the processing container.