| 摘要 |
PURPOSE:To use a silicon nitride film as a stopper for oxide film etching to prevent a film reduction of a ground-work silicon oxide film by a method wherein a silicon nitride film exists between a gate electrode and a sidewall formed in its sidewall. CONSTITUTION:A gate electrode 103 with a silicon oxide film 104 is formed. Next, a silicon nitride film 107 is formed. Next, a silicon oxide film 105 is formed. Next, the silicon oxide film 105 is etched. At this time, a sidewall 106 is formed in sidewalls of the gate electrodes 103, 104 of which an oxide film is apparently thickened to perform anisotropic etching. At this time, as the selection ratio of the silicon nitride film 107 to the silicon oxide film 105 is about three, the silicon nitride film is used as a stopper and the etching does not come to progress at the time of exposure. Therefore, film reduction of the silicon oxide film 104 on the gate electrode 103 is prevented. |
