Patent ID: 8129282

Claim:
A plasma etching method for plasma etching an oxide film formed on a substrate through a hard mask layer by using a plasma etching apparatus, the plasma etching apparatus including a vacuum-evacuable processing chamber, a lower electrode disposed in the processing chamber and serving as a mounting table for the substrate, an upper electrode disposed to face the lower electrode in the processing chamber, a first high frequency power supply connected to the upper electrode and applying a first high frequency power to the upper electrode, and a second frequency power supply connected to the lower electrode and applying a high frequency power for bias to the lower electrode, the method comprising the steps of: loading the substrate into the processing chamber, and mounting the substrate on the lower electrode; plasma etching a hard mask layer by using a photoresist as a mask; supplying a processing gas containing C x F y , C 4 F 8 , a rare gas and O 2 , wherein x is an integer equal to or less than 3 and y is an integer equal to or less than 8; generating a plasma of the processing gas by applying the first high frequency power to the upper electrode; applying the second high frequency power for bias to the lower electrode; applying a DC voltage to the upper electrode; and plasma etching the oxide film by using the hard mask layer as a mask, wherein said plasma etching the oxide film is carried out by using the generated plasma, wherein a ratio of C x F y /C 4 F 8 is within a range from 1 to 3, and wherein a ratio of O 2 to the rare gas is equal to or lower than 1/20 and equal to or greater than 2/90.