Granted Patent B2

US 7,235,476 · App. 11/061,900 · Granted Jun 26, 2007

Abstract

Claims (39)

1. A method of manufacturing a semiconductor device comprising the steps of:

forming a first insulating film on first and second regions of a semiconductor substrate;

forming a first conductive film on the first insulating film;

forming a second insulating film on the first conductive film;

forming on the second insulating film a first resist pattern having a first window in a contact region on the first conductive film of the first region;

forming a first opening, through which the contact region exposes, in the second insulating film under the first window, by etching the second insulating film while using the first resist pattern as a mask;

removing the first resist pattern;

forming a third insulating film on the first conductive film exposed from the first opening;

forming a second conductive film on the second and third insulating films;

forming a second resist pattern having a first resist portion in the first region and a second resist portion in the second region, the first resist portion having a size to cover the first opening;

etching the first and second conductive films and the second insulating film while using the second resist pattern as a mask, thus making the first and second conductive film under the first resist portion into a first and second conductor respectively, making the first and second conductive film under the second resist portion into a floating gate and a control gate respectively, and making the second insulating film into an intermediate insulating film;

removing the second resist pattern;

forming a third resist pattern in the first and second regions, where the third resist pattern having, in the first region, a second window that has a size to encompass the contact region of the first conductor;

selectively removing the second conductor under the second window by etching the second conductor while using the third resist pattern as a mask;

removing the third resist pattern;

exposing the contact region by removing the third insulating film on the contact region of the first conductor;

forming an inter-layer insulating film to cover the first conductor;

forming a hole in the inter-layer insulating film on the contact region of the first conductor; and

forming a conductive plug in the hole, the conductive plug being electrically connected to the contact region of the first conductor.

2. The method according to claim 1 , wherein an ONO film is employed as the second insulating film; and in the step of forming the third insulating film, an oxide film is formed by thermally oxidizing a surface of the first conductive film exposed through the first opening, and the oxide film is used as the third insulating film.

3. The method according to claim 2 , wherein a polysilicon film is employed as the first conductive film.

4. The method according to claim 1 , wherein the first conductor is made into a first gate electrode in the step of forming the first and second conductors.

5. The method according to claim 4 , further comprising the step of:

forming a device isolation insulating film in the first region of the semiconductor substrate,

wherein, in the step of forming the first and second conductors, the first gate electrode is constructed from a gate and a pad, where the pad being extended on the device isolation insulating film.

6. The method according to claim 5 , wherein, in the step of forming the third resist pattern, the second window is formed in a size to encompass the pad, and in the step of selectively removing the second conductor under the second window, all of the second conductor is removed on the pad.

7. The method according to claim 1 ,

wherein, in the step of forming the first insulating film, the first insulating film is also formed in a third region of the semiconductor substrate;

in the step of forming the second insulating film, the second insulating film is also formed on the first insulating film in the third region;

in the step of forming the first opening in the second insulating film, the first and second insulating films are removed from the third region;

in the step of forming the third insulating film, the third insulating film is also formed in the third region of the semiconductor substrate;

in the step of forming the third resist pattern, a third resist portion of the third resist pattern is formed on the third region; and

in the step of etching the second conductor by using the third resist pattern as a mask, the second conductive film under the third resist portion is made into a first gate electrode.

8. The method according to claim 7 , wherein an ONO film is employed as the second insulating film; and in the step of forming the third insulating film, an oxide film is formed by thermally oxidizing each surface of the semiconductor substrate in the third region and the first conductive film, and the oxide film is used as the third insulating film.

9. The method according to claim 1 , wherein, in the step of forming the third resist pattern, the second window is formed in a size to be encompassed in the first opening; and in the step of selectively removing the second conductor under the second window, a second opening is formed in the second conductor under the second window.

10. The method according to claim 9 , further comprising the step of:

forming a silicide layer on an upper surface of the second conductor.

11. The method according to claim 10 , wherein, in the step of forming the silicide layer, the silicide layer is also formed on an upper surface of the first gate electrode and on a surface layer of the semiconductor substrate beside the first gate electrode.

12. The method according to claim 10 , wherein a cobalt silicide layer or a nickel silicide layer is formed as the silicide layer.

Assignments (6)