Spannungsfilme

Spannungsfilme are thin films that contain residual mechanical stress relative to the substrate on which they are deposited. The stress can be tensile or compressive and arises from a combination of intrinsic factors during film growth and thermal effects after deposition. Intrinsic stresses develop from microstructural evolution, grain boundaries, and atomic peening during deposition, while thermal stresses originate from differences in thermal expansion coefficients between film and substrate when the structure cools from processing temperatures.

The presence of Spannungsfilme influences coating adhesion, morphology, and mechanical integrity. Tensile stress may promote cracking or wrinkling, whereas compressive stress can cause buckling or delamination, especially in constrained geometries or thicker films.

Characterization employs several methods. The wafer-curvature technique, together with the Stoney equation, provides an average film stress for thin films on large substrates. X-ray diffraction measures lattice strain to infer stress, while Raman spectroscopy can probe stress in certain materials. Microscopy and spectroscopic methods such as transmission electron microscopy can reveal local stress fields.

Control and mitigation of Spannungsfilme are key in device fabrication. Adjusting deposition parameters (temperature, rate, energy), tuning film thickness, introducing stress-compensating layers, or applying post-deposition annealing can reduce undesirable stresses. In applications such as semiconductor interconnects, optical coatings, MEMS, and flexible electronics, managing film stress improves reliability and performance.