Method for manufacturing interpoly dielectric
AssigneeMacronix International Co., Ltd.
InventorJung-Yu Hsieh
Life of this patent
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Abstract
Roughly described, a floating gate memory cell is fabricated by forming an oxide-nitride dielectric layer above a floating gate of the memory cell and in an oxide growth region not above a floating gate. The nitride layer is removed in the oxide growth region using a mask that protects the nitride layer above the floating gate, and then the bottom oxide layer is removed in the oxide growth region using a wet etch that does not affect the nitride remaining above the floating gate. First and second oxide layers are then formed both above the floating gate and in the oxide growth region, to act as the top layer of ONO above the floating gate and as the gate oxide in the oxide growth region. One of the first and second oxide layers is formed using in-situ steam generation.
Claims19
A method of fabricating a floating gate memory cell on a wafer, comprising the steps of:
- forming a dielectric layer above a floating gate of the memory cell and in an oxide growth region not above a floating gate, the dielectric layer including a bottom oxide layer underlying a silicon nitride layer;
- removing the silicon nitride layer in the oxide growth region using a mask that covers the silicon nitride layer above the floating gate;
- removing the bottom oxide layer in the oxide growth region;
- forming a first oxide layer both above the floating gate and in the oxide growth region and a second oxide layer over the first oxide layer both above the floating gate and in the oxide growth region, one of the first and second oxide layers being formed using in-situ steam generation.
A method of fabricating a floating gate memory cell on a wafer, comprising the steps of:
- forming a dielectric layer above a floating gate of the memory cell and in an oxide growth region not above the floating gate, the dielectric layer including a bottom oxide layer underlying a silicon nitride layer;
- forming a photoresist both over the floating gate and in the oxide growth region over the silicon nitride layer;
- lithographically remove the photoresist in the oxide growth region;
- dry etching the silicon nitride layer using the photoresist as a mask;
- removing the remaining photoresist;
- wet etching the bottom oxide layer in the oxide growth region using the silicon nitride layer as a mask;
- forming a first oxide layer both above the floating gate and in the oxide growth region simultaneously;
- and
- forming a second oxide layer over the first oxide layer both above the floating gate and in the oxide growth region simultaneously,
- wherein one of the first and second oxide layers is formed using in-situ steam generation.
Dependencies are inferred from the claim text.