Method for forming flash memory cell
AssigneeMacronix International Co., Ltd.
InventorsPing-Yi Chang, Wan-Yi Liu, Shu-Li Wu
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Abstract
The present invention provides a method for forming a flash memory cell and comprises following steps. First, a substrate is provided. Then, a first polysilicon layer and a nitride layer are sequentially formed on the substrate. Next, a portion of the nitride layer and the polysilicon layer are removed to form a plurality of holes to expose the substrate. Following, an isolation dielectric is formed in those holes, wherein the isolation dielectric is gibbous in a sidewall of those holes and higher than the first polysilicon layer. Then, the nitride layer on the first polysilicon layer is removed. Last, a second polysilicon layer is conformally formed on the first polysilicon layer and the isolation dielectric.
Claims15
A method for forming a flash memory cell, said method comprising:
- providing a substrate;
- forming a first polysilicon layer on said substrate;
- forming a nitride layer on said first polysilicon layer;
- removing a portion of said nitride layer and said polysilicon layer to form a plurality of holes to expose said substrate;
- forming an isolation dielectric in said holes, wherein said isolation dielectric is gibbous in a sidewall of said holes and higher than said first polysilicon layer;
- removing said nitride layer on said first polysilicon layer;
- and
- conformally forming a second polysilicon layer on said first polysilicon layer and said isolation dielectric.
A method for forming a flash memory cell, said method comprising:
- providing a substrate;
- forming a first polysilicon layer on said substrate;
- forming a nitride layer on said first polysilicon layer;
- removing a portion of said nitride layer and said polysilicon layer to form a plurality of holes to expose said substrate;
- conformlly depositing a dielectric layer on said nitride layer and said substrate;
- using a sputtering process to remove a portion of said dielectric layer and to expose a portion of said nitride layer;
- removing said dielectric layer on said nitride layer, wherein remained said dielectric layer in said holes is gibbous in a sidewall of said holes and higher than said first polysilicon layer;
- removing said nitride layer on said first polysilicon layer;
- and
- conformally forming a second polysilicon layer on said first polysilicon layer and said isolation dielectric.
Dependencies are inferred from the claim text.