Method of processing a sample surface having a masking material and an anti-reflective film using a plasma

A surface processing apparatus is provided. In the apparatus, an etching rate ratio of an organic material such as a BARC of anti-reflective film to a resist of mask forming a pattern, that is, a selective ratio is high, the anti-reflective film being a means for forming the pattern with a high accuracy in surface processing of a semiconductor. In the surface processing apparatus using a plasma, a deposition gas is added to a light element of hydrogen as the etching gas. Ions accelerated by a bias electric power supply accelerate etching reaction. Sputtering at edges of the mask can be reduced by using the light element of hydrogen as the etching gas, and the selective ratio of the anti-reflective film to the masking material can be increased by mixing the deposition gas with the hydrogen.