Abstract
Potential problems induced by the multilayered manufacturing process pose a serious threat to the long-term reliability of MEMSCAP® actuators under in-service thermal cycling. Damage would initiate and propagate in different material layers because of a large mismatch of their thermal expansions. In this research, residual stresses and variations of design parameters induced by metal multi-user micro electromechanical system processes (MetalMUMPs) were examined to evaluate their effects on the thermal fatigue lifetime of the multilayer structure and, thus, to improve MEMSCAP® design. Since testing in such micro internal structure is difficult to conduct and traditional testing schemes are destructive, a numerical subdomain method based on a finite element technique was employed. Thermomechanical deformation from metal to insulator layers under in-service temperature cycling (obtained from the multiphysics model of the entire actuator, which was validated by experimental and specified analytical solutions) was accurately estimated to define failures with a significant efficiency and feasibility. Simulation results showed that critical failure modes included interface delamination, plastic deformation, micro cracking, and thermal fatigue, similarly to what was concluded in the MEMSCAP® technical report.
Highlights
Multilayer structures have been widely used in various micro- and nanoscale components because of their better electrical continuity and thermal insulation
The thermal fatigue lifetime of a Si–Ceramic–Cu interface was predicted with the finite element method (FEM) by Rodriguez and Shammas [8]
The simulation results for maximum levels of von Mises stress concentration along the copper and polysilicon interface for the five cases are shown in Figure 14; Table 2 presents a comparison of maximum strains and thermal fatigue lifetime in these cases
Summary
Multilayer structures have been widely used in various micro- and nanoscale components because of their better electrical continuity and thermal insulation. Little attention was given to the effect of the manufacturing process (both residual stresses and variation of design parameters) on the long-term reliability of multilayer structures This factor is important for failure initiation and propagation in microscale devices because of the size and surface effects, as emphasised by the manufacturing manual and the reliability analysis reports of MEMSCAP® actuators in the Polynoe program [13,14,15]. The objective of this research was to evaluate the effects of these manufacturing factors on thermomechanical deformation mechanisms as well as on failure onset and propagation in a multilayer structure These variables are of vital importance for the design and analysis of micro actuators and for the improvement of their performance in the submicron scale. The verification of the subdomain model was granted by the adjusted geometry, material, and dynamic loadings that were obtained from the functional model of actuators, which was validated by experimental measures and specified analytical solutions
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
