| abstract |
The invention provides an etching method for selectively etching a first region made of silicon oxide with high accuracy. In this method, the first region R1 composed of silicon oxide is selectively etched with respect to the second region R2 composed of silicon nitride by plasma treatment of the object to be processed. 2 region R2, a first region R1 in which the recess is buried, and a mask MK disposed on the first region R1; the method includes: a first step of generating a plasma of a processing gas containing a fluorocarbon gas; and In the second step, the first region is etched by the free radical of the fluorocarbon compound contained in the deposit. In the second step, the high-frequency power that is helpful for the formation of the plasma is applied in a pulsed manner; and these steps are repeated. |