Patent ID: 8609549

Claim:
A plasma etching method comprising: preparing a substrate having a photoresist layer of a predetermined pattern, an organic bottom anti-reflection coating (BARC) film formed below the photoresist layer, an SiON film formed below the BARC film, and an amorphous carbon film formed below the SiON film, and a silicon oxide film or a silicon nitride film formed below the amorphous carbon film; a first etching step of etching the BARC film and the SiON film by using the photoresist layer as a mask, wherein a part of the photoresist layer remains on the BARC film after the first etching step; a second etching step of etching the amorphous carbon film by using the remaining photoresist layer, the BARC film and the SiON film as a mask, wherein a part of the SiON film remains after the second etching step and a ratio of a film thickness of the amorphous carbon film to a film thickness of the remaining SiON film is equal to or smaller than about 14; and a third etching step of etching the silicon oxide film or the silicon nitride film by using the remaining SiON film and the amorphous carbon film as a mask, wherein at least the first etching step and the second etching step are performed using a plasma etching apparatus that includes a lower electrode provided in a processing chamber for mounting the substrate thereon, an upper electrode provided in the processing chamber to face the lower electrode, and a RF power supply for applying a RF power between the lower electrode and the upper electrode, wherein a DC voltage is applied to the upper electrode while the BARC film and the SiON film are etched in the first etching step and wherein no DC voltage is applied to the upper electrode while the amorphous carbon film is etched in the second etching step.