Mechanisms for forming semiconductor device structure with feature opening

A method for forming a semiconductor device structure, comprising:

• forming a dielectric layer over a semiconductor substrate;
• forming a hard mask layer over the dielectric layer, wherein the hard mask layer is a metal-containing layer;
• forming a mask layer over the hard mask layer;
• patterning the mask layer by using a photoresist layer;
• removing the photoresist layer;
• performing a plasma etching process to etch the hard mask layer to form an opening after the photoresist layer is removed, wherein a gas mixture used in the plasma etching process includes a nitrogen-containing gas, a halogen-containing gas, and a carbon-containing gas, the gas mixture has a volumetric concentration of the nitrogen-containing gas in a range from about 20% to about 30%, a volumetric concentration ratio of the carbon-containing gas to the halogen-containing gas in the gas mixture is equal to about 0.3, and the patterned mask layer is used as an etching mask while the hard mask layer is etched to form the opening;
• etching the dielectric layer through the opening in the hard mask layer to form a feature opening in the dielectric layer;
• and
• forming a conductive material in the feature opening.

A method for forming a semiconductor device structure, comprising:

• forming a dielectric layer over a semiconductor substrate;
• forming a hard mask layer over the dielectric layer, wherein the hard mask layer is a metal-containing layer;
• forming a mask layer over the hard mask layer;
• patterning the mask layer by using a photoresist layer;
• removing the photoresist layer;
• performing a plasma etching process to etch the hard mask layer to form an opening with a vertical sidewall after the photoresist layer is removed, wherein a gas mixture used in the plasma etching process includes a nitrogen-containing gas, a halogen-containing gas, and a carbon-containing gas, the gas mixture has a volumetric concentration of the nitrogen-containing gas in a range from about 20% to about 30%, a volumetric concentration ratio of the carbon-containing gas to the halogen-containing gas in the gas mixture is equal to about 0.3, and the patterned mask layer is used as an etching mask while the hard mask layer is etched to form the opening;
• etching the dielectric layer through the opening in the hard mask layer to forth a feature opening in the dielectric layer;
• and
• forming a conductive material in the feature opening.