| 摘要 |
PURPOSE:To enable to form an insulating thin film having stabilized dielectric strength by a method wherein nitrogen ions are implanted to a silicon substrate to form a silicon nitride film, and after O2 ions are implanted to the part lower than the interface between the silicon nitride film and the silicon substrate, a heat treatment is performed at the specified temperature. CONSTITUTION:N2 ions are implanted extremely thin at the extent of 100Angstrom film thickness to the surface of the silicon substrate 1. The ion implantation condition is to form the silicon nitride film 3 only in the surface layer in a short time by enlarging the current quantity by a voltage. Then, O2 ions are implanted to the lower part of the silicon nitride film 3 to make film thickness thereof to the extent of 300Angstrom . As the ion implantation condition, a silicon oxide film 4 is formed under the silicon nitride film 3 according to a comparatively high accelerating voltage. In this condition as it is, the films can not be called yet as the regular silicon nitride film or silicon oxide film, and because only impurity ions thereof are driven in the silicon substrate 1, the heat treatment is performed for 30min at the temperature 1,100 deg.C in N2 gas or O2 gas to demarcate the silicon nitride film 3 of 100Angstrom film thickness and the silicon oxide film 4 of 300Angstrom film thickness. |
