Fig. 1. A microheater fabricated with a type-II Pt film as the resistor. (a) SEM image of the microheater. (b) Cross-sectional sketch of the microheater. The operating area of the microheater was designed as a multilayer suspended film structure that was ~700 nm thick.

Fig. 2. Microstructures of the one-step and two-step sputtered Pt films. (a) SEM image of the as-deposited type-I Pt film. Black arrows indicate the faceted grains formed during deposition. (b) and (c) SEM images of the type-I Pt film annealed at 1000 °C for 2 h. (d) SEM images of the as-deposited type-II Pt film. (e) and (f) SEM images of the type-II Pt film annealed at 1000 °C for 2 h. (g) Mean grain sizes of the Pt films annealed at different temperatures. (h) XRD patterns of the Pt films.

Fig. 3. Degradation test of the SiNx-passivated two-step Pt film in SEM. (a) SEM image of the Pt film after the voltage was increased to a maximum of 2.7 V for 12 min. (b) Enlarged SEM image of the Pt film region outline by the red box in (a). The failure position of the Pt film is indicated in the figure. (c) Normalized resistance changes in the Pt film as a function of heating temperature obtained by Raman spectroscopy. (d) Finite element analysis of the microheater temperature distribution under a constant voltage of 2.7 V. (For interpretation of the references to color in this figure, the reader is referred to the web version of this article.).

Fig. 4. In situ BF-STEM study of the degradation behaviors in the SiNx-passivated Pt film at different temperatures. (a) and (g) Images of the film prior to the degradation test. Initial GB voids exist in the Pt film. (b-f) Images of the film degraded at different temperatures. (h) Low-magnification image of the failure region after being held at 1080 °C for 40 min.

Fig. 5. Cross-sectional (S)TEM characterization of the Pt film after in situ degradation in SEM. (a) HAADF-STEM image of the bulging region. (b) HAADF-STEM image of an unbulging region. (c) and (d) Bright-field TEM images of a GB void and an IG void. (e) HAADF-STEM image of an IG void.

Fig. 6. The facet features of IG voids. (a) BF-STEM image of voids in the Pt film. (b) Equilibrium shape of a faceted Pt crystal, as calculated with Wulffmaker. (For interpretation of the references to color in this figure, the reader is referred to the web version of this article.)

Fig. 7. Strain and stress distributions in the microheater simulated with a two-dimensional cross-sectional model. (a) Elastic strain ε distribution in the microheater. (b) Normal stress σxx distribution in the microheater. (c) Sketch of the stress/strain states in different layers.

Fig. 8. BF-TEM image of a region near the edge of the degraded Pt film, viewed from the Z direction, with the evolution plot of σxx along the X-axis overlaid.

Fig. 9. The evolutions of the diffusivities as functions of temperature for the lattice, GB, and dislocation core diffusions in Pt.

Fig. 10. BF-STEM images of Pt films at the same temperature (1080 °C) under different loading methods. (a) Thermal conduction heating. (b) Self-Joule heating.