Gas phase etch with controllable etch selectivity of Si-containing arc or silicon oxynitride to different films or masks

A method for the dry removal of a material on a microelectronic workpiece, comprising:

• providing a workpiece having a multi-layer mask, the multilayer mask having an opening with a film stack exposed through the opening at a bottom of the opening, the multilayer mask including:
• (i) a patterned layer, and (ii) a target layer on top of the patterned layer, the target layer formed of a material which includes silicon and an organic material;
• operating a dry etch chamber to selectively remove at least a portion of the target layer from the top of the patterned layer by performing the following:
• holding the workpiece on a workpiece holder and exposing the target layer to a chemical environment containing a gaseous mixture that includes N, H, and F at a first workpiece setpoint temperature to chemically alter a surface region of the target layer and to chemically alter a depth within the target layer such that, after the exposing, the target layer is on top of the patterned layer and includes a chemically altered surface region and a chemically altered depth within the target layer;
• and
• after the exposing of the target layer at the first workpiece setpoint temperature, elevating the temperature of the workpiece to a second workpiece setpoint temperature, wherein prior to elevating the temperature of the workpiece to the second workpiece setpoint temperature, the target layer includes the chemically altered surface region and the chemically altered depth within the target layer on top of the patterned layer, and after the elevating at least a portion of the chemically altered depth of the target layer is removed,
• wherein prior to the exposing to the chemical environment and the elevating the temperature:
• (a) the opening extends through both the patterned layer and the target layer, (b) side surfaces of the patterned layer are exposed and face the opening, and (c) side surfaces of the target layer are exposed and face the opening above the side surfaces of the patterned layer,
• wherein the exposing to the chemical environment and the elevating the temperature is performed one or more times to selectively remove the target layer with respect to the patterned layer until the target layer is completely removed, and after the target layer is completely removed, portions of the patterned layer remain with the opening therethrough and with the film stack exposed through the opening in the patterned layer, and
• wherein the exposing to the chemical environment and the elevating the temperature also selectively removes the target layer relative to a top layer of the film stack exposed through the opening.