Multiscale roughness and modeling of MEMS interfaces

Abstract

Investigation of contact and friction at multiple length scales is necessary for the design of surfaces in sliding microelectromechanical system (MEMS). A method is developed to investigate the geometry of summits at different length scales. Analysis of density, height, and curvature of summits on atomic force microscopy (AFM) images of actual silicon MEMS surfaces shows that these properties have a power law relationship with the sampling size used to define a summit, and no welldefined value for any is found, even at the smallest experimentally accessible length scale. This behavior and its similarity to results for fractal Weierstrass-Mandelbrot (W-M) function approximations indicate that a multiscale model is required to properly describe these surfaces. A multiscale contact model is developed to describe the behavior of asperities at different discrete length scales using an elastic single asperity contact description. The contact behavior is shown to be independent of the scaling constant when asperity heights and radii are scaled correctly in the model.

Slip flow and heat transfer in microbearings with fractal surface topographies

“…In practice, the roughness can be characterized by atomic force microscope (AFM), scanning tunneling microscope (STM) and scanning electron microscope (SEM) [1]. The power law behavior obtained from AFM images for MEMS surfaces was similar to fractal Weierstrass-Mandelbrot (W-M) surface results [36]. Chen et al [37,38] successfully used fractal Weierstrass-Mandelbrot function to characterize the multiscale self-affine roughness in microchannels.…”

Microtribological Performance of Au–MoS2 and Ti–MoS2 Coatings with Varying Contact Pressure

“…For a little more than a decade, the testing of nano-and micro-scale sliding contacts has been an important research area that seeks to improve the tribological performance of nano/micro-devices and to have a better understanding of a material's behavior during single and multi-asperity contacts [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]. Due to their applications in hard drives, diamond-like carbon (DLC) coatings have been well studied for their tribological behavior at these small length scales [12][13][14][15][16][17][18].…”

An analysis of three-dimensional elasto-plastic sinusoidal contact

“…Elasto-plastic sinusoidal contact has recently become more important with the development of several multiscale contact models [6][7][8][9][10][11][12]. A model of elasto-plastic sinusoidal contact would be very useful to these multiscale contact models.…”