Online Stoney Calculator 5.0

Film stress from the change in substrate curvature

Si

Mechanical stress

— MPa

Δ(1/R)—1/m

R₁—m

R₀—m

Δx = Beam distance change at the detector of SIG500SP / SIG2000VT

µm

d_subSubstrate thickness

µm

d_filmFilm thickness

nm

E_subYoung's modulus

GPa

ν_subPoisson's ratio

–

E and ν come from the selected material and can be changed. Material data is not guaranteed.

aBeam spacing

mm

LDetector distance

cm

a is the beam spacing on the sample.

Material

R₀Radius before

m

Explanation of the measurement: two laser beams on a flat wafer with spacing a and detector distance L, and the same beams after the wafer bends under a stressed film. The Stoney equation gives the film stress from the change in curvature, and the curvature change is (x1 − x0) / (2 a L).