Method for roughness improvement and selectivity enhancement during arc layer etch using hydrogen

A method of dry developing a multi-layer mask on a substrate, comprising:

• disposing a substrate comprising a multi-layer mask in a plasma processing system, wherein the multi-layer mask has a patterned layer defining an open feature pattern overlying a silicon containing ARC (anti-reflective coating) layer;
• establishing a flow of a process gas to the plasma processing system, the process gas containing:
• a first gaseous molecular constituent composed of C, F and optionally H,
• an optional second gaseous molecular constituent composed of C, F, and optionally H, the second gaseous molecular constituent having a different carbon-to-fluorine ratio than the first gaseous molecular constituent, and
• a third gaseous molecular constituent containing atomic hydrogen, diatomic hydrogen, or a CxHy-containing gas, wherein x and y are real numbers greater than zero;
• selecting a process condition specifying a flow rate for each molecular constituent that increases an etch selectivity, measured as the ratio of the etch rate of the silicon containing ARC layer to the etch rate of the patterned lithographic layer, relative to a nominal etch selectivity achievable using the process condition while excluding the introducing of the third gaseous molecular constituent;
• igniting plasma from the process gas using a plasma source in accordance with the process condition;
• and
• exposing the substrate to the plasma to extend the open feature pattern of the patterned layer into the silicon containing ARC layer.