Patent attributes
Methods of etching silicon nitride material, and more particularly, etching nitride selective to silicon dioxide or silicide, are disclosed. The methods include exposing a substrate having silicon nitride thereon to a plasma including at least one fluorohydrocarbon and a non-carbon containing fluorine source such as sulfur hexafluoride (SF6). The plasma may also include oxygen (O2) and the fluorohydrocarbons may include at least one of: trifluoromethane (CHF3), difluoromethane (CH2F2), and methyl fluoride (CH3F). In an alternative embodiment, the plasma includes one of hydrogen (H2) and nitrogen trifluoride (NF3) and one of tetrafluoromethane (CF4) and octafluorocyclobutane (C4F8). The methods are preferably carried out using a low bias voltage, e.g. <100 V.
