Patent attributes
In a method of fabricating a semiconductor device, an additive gas is mixed with an etching gas to reduce a fluorine ratio of the etching gas. The etching gas having a reduced fluorine rate is utilized in the process for etching a nitride layer formed on an oxide layer to prevent the oxide layer formed below the nitride layer from being etched along with the nitride layer. The method comprises primarily etching an exposed charge storage layer using an etching gas; and secondarily etching the charge storage layer using the etching gas under a condition that a ratio of fluorine contained in the etching gas utilized in the secondary etching step is less than a ratio of fluorine contained in the etching gas utilized in the primary etching step. Thus, the tunnel insulating layer formed below the charge storage layer is not damaged when the charge storage layer is patterned.
