| 摘要 |
PURPOSE:To prevent an insulating film from being deteriorated in with stand voltage caused by damages on it in later heat treatment, by annealing a first conductive film in advance at a temperature of the later heat treatment and then forming a thin insulating film thereon. CONSTITUTION:A MOS transistor is formed on a p-type Si substrate 1. A n<+> type polycrystal Si accumulation electrode 9 is then formed above a source region 6, extending from a word line 5a of a self cell to the upper part of a word line 5b of a neighboring cell. Then, the electrode 9 is annealed at a temperature higher than that of heat treatment which is performed on the electrode 9 in a later manufacturing process. Crystal grains in a polycrystal Si film, which forms the electrode 9 in this process, grow to become balanced in their sizes at said temperature, so that a n<+>type polycrystal Si accumulation electrode 109, in which the crystal grains grow to become enlarged, is obtained. A dielectric film 10 comprising two layers of thin Si2N4 and SiO2 films is formed on a main surface of the substrate 1. Stress effected on the film 10 by heat history in the later manufacturing process is reduced, and the insulating film can be prevented from being deteriorated in withstand voltage caused by this stress.
|
