A method for forming via holes in an etch layer disposed below a patterned organic mask with a plurality of patterned via holes is provided. The patterned organic mask is treated by flowing a treatment gas comprising H2. A plasma is formed from the treatment gas. The patterned via holes are rounded to form patterned rounded via holes by exposing the patterned via holes to the plasma. The flow of the treatment gas is stopped. The plurality of patterned rounded via holes are transferred into the etch layer.