| 摘要 |
PROBLEM TO BE SOLVED: To provide a semiconductor element which is provided with a buffer layer of good interface characteristics and film characteristics for preventing diffusion of a metal element from a ferroelectrics film to a silicon substrate, by providing an oxynitride layer as a buffer layer between the ferroelectrics film and the silicon substrate. SOLUTION: An SiON film 3 is formed as a buffer layer on a silicon substrate 1, and a ferroelectric film 4 and a gate insulating film 5 are formed into an island-shape on the SiON film 3. Since the SiON film is tighter in structure than a silicon oxide film, the ability for suppressing the diffusion of a metal element constituting a ferroelectrics is high. By controlling the nitrogen concentration in the film to 10% or below, interface characteristics and in-film fixed charge density which is about the same level as the silicon oxide film are provided. So, by using the SiON film, the metal diffusion from a ferroelectrics is prevented with a film which is thinner than the silicon oxide film while such interface and film characteristics of as almost the same level of the silicon oxide film are provided.
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