Methods for fabricating a semiconductor chip having CMOS devices and fieldless array

摘要

A method for etching an oxide-nitride-oxide (ONO) layer fabricated on a semiconductor wafer, the ONO layer including a lower oxide layer, a nitride layer located over the lower oxide layer, and an upper oxide layer located over the nitride layer. The method includes the steps of removing the upper oxide layer and a portion of the nitride layer using an isotropic plasma enhanced etch, and then removing the remainder of the nitride layer and a portion of the lower oxide layer using an isotropic plasma enhanced etch, wherein the semiconductor wafer is not exposed through the lower oxide layer. The method can be used to form gate electrodes and diffusion bit liens in a fieldless array of non-volatile memory cells.