Method for the formation of field oxide film in semiconductor device
AssigneeHyundai Electronics Industries Co., Ltd.
InventorSe A. Jang
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Abstract
There are disclosed methods for the formation of field oxide film in a semiconductor device. By the methods, a field oxide film which plays a role of insulation for the separation of device, is formed in a trench formed in a semiconductor substrate. In the methods, an oxide-nitride film is utilized as an oxidation protective film which prevents a pad oxide film and the side well of the trench from being oxidized. As a result, the bird's beak is reduced, which allows to secure the active region more large. In addition, the methods make the field oxide film smooth. Furthermore, increasing the threshold voltage of a field, the field oxide film is superior in punchthrough characteristics. Accordingly, the methods can be applied to fabricate highly integrated semiconductor devices.
Claims8
A method for the formation of field oxide film in a semiconductor device, comprising the steps of:
- covering a semiconductor substrate with a pad oxide film;
- annealing said pad oxide film, so as to form a first oxide-nitride film;
- overlaying said first oxide-nitride film with a polysilicon film and a first nitride film, in due order;
- etching said first nitride film and said polysilicon film to form a hole exposing a predetermined portion of said first oxide-nitride film, and depositing a second nitride film entirely over the resulting structure;
- subjecting said second nitride film to etch back, so as to form a spacer nitride film at either side wall of said hole, and applying an etch process to said predetermined portion, so as to form a trench in said semiconductor substrate, said spacer nitride film and said first nitride film serving as an etch mask;
- annealing said trench to grow a second oxide-nitride film from both the bottom and the side wall of said trench;
- and
- removing only the second oxide-nitride film formed on the bottom of said trench by use of etching, and forming a field oxide film in said trench.
A method for the formation of field oxide film in a semiconductor device, comprising the steps of:
- forming a pad oxide film, a polysilicon film and a first nitride film on a semiconductor substrate, in due order;
- etching said first nitride film and said polysilicon film, to form a hole exposing a predetermined portion of said pad oxide film covering said semiconductor substrate, and depositing a second nitride film entirely over the resulting structure;
- subjecting said second nitride film to etch back, so as to form a spacer nitride film at either side wall of said hole, and applying an etch process to said predetermined portion, so as to form a trench in said semiconductor substrate, said spacer nitride film and said first nitride film serving as an etch mask;
- annealing said trench to grow a second oxide-nitride film from both the bottom and the side wall of said trench;
- and
- removing only the second oxide-nitride film formed on the bottom of said trench by use of etching, and forming a field oxide film in said trench.
Dependencies are inferred from the claim text.