Morphology of diamond films has been controlled via intermediate frequency induction heated microwave plasma chemical vapor deposition (IH-MPCVD), which was transformed with various substrate temperatures (T_sub = 923–1123 K) and CH₄/H₂ ratios (η_c = 0.5–2 vol%). The coupling effects of T_sub and η_c on the structure of diamond films have been studied. At η_c = 0.5 vol%, the sp³/sp² ratio of diamond films reached 98% at 1073 K, surface roughness (R_ms) increased from 50 to 85 nm with increasing T_sub, the maximum hardness (H_a) reached 84 GPa at 973 K, and the maximum Young's modulus (E) reached 642 GPa at 1023 K. The residual stress (σ) was calculated as a function of T_sub and η_c. The quality factor (Q), combining microstructure and mechanical behavior, has been creatively defined to evaluate the quality of diamond films.