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US 2003/0216003 A1Published application
Method of forming flash memory device
OwnerSang Ick Lee, Hyung Hwan Kiminventors
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Abstract
Method of forming flash memory device is disclosed, more particularly, method of forming self-aligned floating gate by performing Chemical Mechanical Polishing (abbreviated as “CMP”) process using slurry having higher polishing selectivity to oxide films than to nitride films and slurry having higher polishing selectivity to polysilicon than to oxide films.
Claims17
A method for forming a flash memory device comprising:
- (a) forming a pad oxide film and a pad nitride film on a substrate;
- (b) selectively pattering the pad nitride film, the pad oxide film and the substrate to form a trench;
- (c) forming a isolation oxide film on the resultant structure;
- (d) performing a CMP process on the isolation oxide film using a first slurry of pH ranging from 2 to 7 until the pad nitride film is exposed to form an isolation oxide film pattern for separating an active region, wherein the first slurry comprises a solvent, an abrasive and a first additive and the first additive is selected from the group consisting of a homo-polymer of hydrocarbon compound including carboxylic acid(—COOH) group, a homo-polymer of hydrocarbon compound including nitro(—NO2) group, a homo-polymer of hydrocarbon compound including amide(—NH—CO—) group, a copolymer of hydrocarbon compound including carboxylic acid(—COOH) group, a copolymer of hydrocarbon compound including nitro(—NO2) group, a copolymer of hydrocarbon compound including amide(—NH—CO—) group and mixtures thereof;
- (e) removing the pad nitride film pattern and the pad oxide film pattern in the active region to expose the substrate in the active region;
- (f) forming a tunnel oxide film on the substrate in the active region by performing an oxidation process;
- (g) forming a polysilicon layer on the resultant structure;
- and
- (h) performing a CMP process on the polysilicon layer using a second slurry of pH ranging from 8 to 11 until the isolation oxide film is exposed to form a floating gate, wherein the second slurry comprises a solvent, an abrasive and a second additive and the second additive comprises ammonium hydroxide or an amine compound.
6 more elements
Dependencies are inferred from the claim text.