Film bulk acoustic wave device

A film bulk acoustic wave device comprising:

• a substrate;
• a dielectric film formed on said substrate;
• a bottom electrode including a conductor formed on said dielectric film and having a density of 10000 (kg/m3) or more;
• a piezoelectric film formed on said bottom electrode and which generates a thickness extension vibration as a main vibration;
• and
• a top electrode including a conductor formed on said piezoelectric film and having a density of 10000 (kg/m3) or more,
• wherein when the thickness of said piezoelectric film is set to 2 h, the thickness of said dielectric film is set to g, the density of said top electrode is set to ρ1×1000 (kg/m3), the thickness of said top electrode is set to d1, the density of said bottom electrode is set to ρ2×1000 (kg/m3), the thickness of said bottom electrode is set to d2, and an equivalent density R is set to R=(ρ1d1/h)+(ρ2d2/h),
• the normalized thickness (g/h) of said dielectric film determined by the thicknesses of said piezoelectric film and said dielectric film is {0.15×R+2.8} or more.

A film bulk acoustic wave device comprising:

• a substrate;
• a dielectric film formed on said substrate;
• a bottom electrode including a conductor formed on said dielectric film and having a density of 10000 (kg/m3) or more;
• a piezoelectric film formed on said bottom electrode and which generates a thickness extension vibration as a main vibration;
• and
• a top electrode including a conductor formed on said piezoelectric film and having a density of 10000 (kg/m3) or less,
• wherein when the thickness of said piezoelectric film is set to 2h, the thickness of said dielectric film is set to g, the density of said top electrode is set to ρ1×1000 (kg/m3), the thickness of said top electrode is set to d1, the density of said bottom electrode is set to ρ2×1000 (kg/m3), the thickness of said bottom electrode is set to d2, and an equivalent density R is set to R=(ρ1d1/h)+(ρ2d2/h),
• the normalized thickness (g/h) of said dielectric film determined by the thicknesses of said piezoelectric film and said dielectric film is {0.023×R+3.5} or more.