Patent ID: 11915932
Assignee: APPLIED MATERIALS, INC.
Field: Semiconductors (Electrical engineering)
Classification: CPC G  H | IPC H

Claim 18:
19. An etching method comprising:
forming a plasma of at least one fluorine-containing precursor to produce plasma effluents, wherein a first bias frequency is applied while forming the plasma;
contacting a substrate housed in a processing region of a semiconductor processing chamber with the plasma effluents, wherein the substrate comprises a photomask, and wherein the photomask comprises at least two layers between a hardmask and a mirror layer of the photomask;
etching a first layer of the photomask, wherein etching the first layer of the photomask exposes a second layer of the photomask;
adjusting the first bias frequency to a second bias frequency, wherein the first bias frequency is greater than or about 10 MHz, and wherein the second bias frequency is less than or about 10 MHz; and
etching the second layer of the photomask.