Patent ID: 7573094

Claim:
A random number generating element comprising: a source region; a drain region; a semiconductor channel provided between the source region and the drain region and having a thin-line portion of a width W and a length L, the width W and the length L satisfying W≦(π/10(μm 2 ))/L; a tunnel insulation film provided on the semiconductor channel; and a conductive fine particle group containing a plurality of conductive fine particles provided on the tunnel insulation film with a surface density not less than 2.5×10 11 cm −2 , the conductive fine particles being charge and discharge by electrons tunneling through the tunnel insulation film, the conductive fine particle group being formed over the semiconductor channel; and a gate region provided over the conductive fine particle group, wherein the following inequalities are satisfied: LWD dot ≧[R Tunnel /R Tunnel (Tox=0.8 nm)] 0.3 nm/T ×exp[0.3 nm×(0.8 nm/ T )×(4π(2 m× 3.1 eV) 1/2 /h )], (q/4 π∈T )≧26 mV, [ D dot ×d 4/3 /( W×L 1/2 )]×[ R Tunnel /R Tunnel (Tox=0.8 nm)] −2/3 ≧8000×2 1/2 (μm −13/6 ) where D dot represents the surface density of the conductive fine particles, d an average diameter of the conductive fine particles, T a thickness of the tunnel insulation film, R tunnel a tunnel resistance of the tunnel insulation film per unit area, R tunnel (Tox=0.8 nm) a tunnel resistance, per unit area, of a tunnel oxide film with a thickness of 0.8 nm, h Plank's constant, q elemental charge, m an effective mass of a tunnel via the tunnel insulation film, and ∈ a dielectric constant of the tunnel insulation film.