Method for eliminating polysilicon residue by tilted ion implantation with oxygen
AssigneeMacronix International Co., Ltd.
InventorsChun-Lien Su, Chun-Chi Wang, Ming-Shang Chen
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Abstract
A method for eliminating polysilicon residue is provided by converting the polysilicon residue into silicon dioxide in two steps. A tilted ion implantation step is performed to implant oxygen ions into the polysilicon residue to rich oxygen containing of the polysilicon residue. An oxygen anneal step is subsequently performed to completely convert the rich oxygen containing polysilicon residue into silicon dioxide that can eliminate the conductivity of the polysilicon residue and prevent oxygen encroachment occurring.
Claims16
A method for eliminating polysilicon residue on a sidewall, comprising the steps of:
- performing a tilted ion implantation step to implant oxygen ion into the polysilicon residue on the sidewall;
- and
- performing an oxygen anneal step to fully convert the polysilicon residue into a silicon dioxide.
A method for eliminating polysilicon residue adapted for a semiconductor substrate including a plurality of parallel word lines, the polysilicon residue is on the sidewall of an insulating layer between two word lines and connected the word lines, comprising the steps of:
- performing a tilted ion implantation step to implant oxygen ions into the polysilicon residue on the sidewall;
- and
- performing an oxygen anneal step to fully convert the polysilicon residue into a silicon dioxide.
A method of fabricating a semiconductor memory device, at least comprising the steps of:
- forming a gate oxide layer, a first polysilicon layer and a nitride layer on a semiconductor substrate;
- patterning the nitride layer, the first polysilicon layer and the gate oxide layer;
- forming an insulating layer over the semiconductor substrate;
- removing portion of the insulating layer until exposing the nitride layer;
- removing the nitride layer;
- forming a second polysilicon layer on the first polysilicon layer and adjacent portion of the insulating layer;
- forming a dielectric layer, a third polysilicon layer and a conductive layer over the semiconductor substrate;
- patterning the conductive layer, the third polysilicon layer, the dielectric layer, the second polysilicon layer and the first polysilicon layer to form a plurality of parallel word lines, and a polysilicon residue is formed on the sidewall of the insulating layer between the word lines;
- performing a tilted ion implantation step to implant oxygen ions into the polysilicon residue;
- and
- performing an oxygen anneal step to convert the polysilicon residue into a silicon dioxide.
Dependencies are inferred from the claim text.