Method for dry etching compound materials

A method for treating a substrate, comprising:

• receiving a substrate in a vacuum process chamber, the substrate comprising a III-V film layer disposed on the substrate, the III-V film layer comprising
• an exposed surface,
• an interior portion underlying the exposed surface, and
• one or more of the following:
• Al, Ga, In, N, P, As, Sb, Si, or Ge;
• treating the exposed surface using a chlorine-based plasma pre-treatment to form a passivation layer on the exposed surface;
• treating the substrate with a hydrogen-based plasma treatment to form a hydrogen interface layer between the passivation layer and the interior portion;
• removing the passivation layer and the hydrogen interface layer, using a chlorine-based plasma treatment, to expose the interior portion;
• and
• repeating the treating of the exposed surface, the treating of the substrate, and the removing of the passivation layer and the hydrogen interface layer until a predetermined amount of the III-V film layer is removed from the substrate.

A method for treating a substrate, comprising:

• receiving a substrate in a vacuum process chamber, the substrate comprising a III-V film layer disposed on the substrate, the III-V film layer comprising
• an exposed surface,
• an interior portion underlying the exposed surface, and
• one or more of the following:
• Al, Ga, In, N, P, As, Sb, Si, or Ge;
• altering the chemical composition of the exposed surface and a fraction of the interior portion of the III-V film layer to form an altered portion of the III-V film layer using a hydrogen-based plasma treatment;
• removing the altered portion of the III-V film layer using a halogen-based plasma treatment;
• purging the vacuum process chamber of halogen-based chemistry from the halogen-based plasma treatment;
• and
• repeating the altering of the chemical composition of the exposed surface, the removing of the altered portion of the III-V film layer, and the purging the vacuum process chamber of the halogen-based chemistry until a predetermined amount of the III-V film layer is removed from the substrate.