Stoney Stress & Substrate Warping
Compute the equibiaxial film stress from a measured substrate radius of curvature, or predict the resulting wafer bow for a target stress. 12 substrate materials.
Validation: 2 / 2 reference cases passing in build 390e714 → /validation#stoney-stress
Stoney equation (1909) implementation with 12 substrate mechanical models (Si, glass, polymers). Two directions: σ → R and R → σ. Includes sag calculation and a thin-film-limit validity check.