Micromachined structures with diameters ranging from 50 — 100 μm have been applied to the measurement of the microscale shearing forces present at the wafer-pad interface during chemical mechanical polishing (CMP). The structures are 80 μm high poly-dimethyl-siloxane posts with bending stiffnesses ranging from 1.6 to 14 μN/μm. The structures were polished using a stiff, ungrooved pad and 3 wt% fumed silica slurry at relative velocities of approximately 0.5 m/s and downforces of approximately 1 psi. Observed lateral forces on the structures were on the order of 5–500 μN, and highly variable in time.

The topology of conventional noble-metal-coated switch counterfaces creates modes of switch failure via fouling, arcing, and local melting when impacted. To avoid these failure phenomena, compliant conductive contact surfaces of vertically aligned multi-wall nanotube arrays grown on conductive substrates have been fabricated. Infiltration of the array by noble metal results in a robust compliant switch contact surface. Cyclic hot-switch testing of the nanotube based switch, via modified nano-indentation, results in performance surpassing conventional designs with stable resistance of 0.4Ω over 3000 cycles. Investigating the physical performance of the array shows the array is compacted less than 3% over the first 500 cycles with no observable compaction through the remaining cycles. The improvement in performance of the nanotube based switch is attributed to the ability for the compliant contact surface to conform to the probe tip geometry, increasing the effective contact surface area.

In Ultrasonic Force Microscopy, the mechanical diode response refers to the quasistatic cantilever deflexion in the presence of surface out-of-plane ultrasonic vibration of sufficiently high amplitude. The effect has been described by introducing ultrasonic-amplitude-dependent tip-sample force-distance curves [Phys. Rev. 61 (2000) 13997]. Here, we demonstrate that the ultrasonic hysteresis phenomenon is qualitatively explained taking into account that for certain ultrasonic amplitudes, the modified tip-sample forces lead to two stable quasi-static equilibrium states, separated by an energy barrier. Experimental UFM data obtained on mica at ambient conditions are discussed in terms of ultrasonic-induced quasi-static equilibrium states, taking into account the role of the surface water layer.

Ultrasonic Force Microscopy and Friction Force Microscopy have been applied to the characterization of the elastic and tribological responses of poly(acrylic acid) hydrogels at ambient conditions. The gels were prepared by free radical polymerization of acrylic acid monomers partially neutralized by sodium hydroxide, using N, N'-methylen-bis-acrylamide as a crosslinker. Nanoscale domains with different stiffness and friction are observed. Increasing the amount of crosslinker leads to the formation of smaller, more densely packed domains. The domains with higher stiffness also exhibit higher friction and lower topographic high. The results can be understood by assuming that (i) neutralization by sodium hydroxide leads to the formation of both acrylic acid and sodium acrylate polymeric strands (ii) the observed domains differ in their acrylic acid / sodium acrylate content. In the acrylic acid rich domains, hydrogen bonding among the polymeric strands explains a higher stiffness and lower topography. In the sodium acrylate rich domains, lubrication by water molecules linked by solvation to the sodium counterions accounts for a lower friction.

Solid lubricant properties of carbon onions prepared from diamond nanoparticles through a heat treatment at 1700°C have been examined at high temperatures up to 300°C in air and vacuum. Sliding friction between a silicon disk on which carbon onions were dispersed and a stainless steel ball was measured by means of ball-on-disk type friction testing. Friction coefficients in vacuum decreased with temperatures and became stable above 100°C for longer service lives. On the contrary to this, friction coefficients in air increased with temperatures despite Raman spectroscopic analysis showed that the structure of carbon onions were stable in dry air up to 300°C.

An application of the nuclear kinematics selective reaction is the usage of the recoil nuclear reaction in generating radioactive ion beams which may de used for MEMS and fine machinery parts labeling used for ultra thin layer activation techniques. The classical Thin or Ultra Thin Layer method relies in creation of a very thin layer on the technologic surface that to exhibit radioactivity of short life radioisotopes. For classical material loss applications concentrations of the order of ppb of different material generated by nuclear reaction were offering plenty of gamma or X radiation to be easily detected over the natural background level directly by a radiation gauge placed above the entire functional mechanism, or by accumulating these in the third tribologic medium – a lubricant or a fluid. In the case of MEMS devices the material concentrations are required to be high enough in order to produce a good radioactive signal or other methods based on resonant energies on isotopic materials may be used such as particle activated prompt gamma, connected with the possibility of the MEMS device of removing from the spot of the dislocated material that becomes technologically useless but carrying out tracer material. There are various possibilities of applying tracer materials on the MEMS devices in order to clearly determine in-situ and in operation the material loss and to correlate with the operation regime.

The addition of water results in the higher wear rate of gold compared to experiments performed in the ambient environment (approximately 60% humidity). This higher wear rate in water has been observed with the AFM, Hysitron Triboindenter, and additionally in single pass scratch tests performed with the Taber Shear/Scratch tester. These tests were preformed using silicon nitride cantilevers on the AFM and a conical diamond tip in the Taber instrument. Tests performed in the ambient atmosphere resulted in slightly reduced surface roughness, while much higher wear rate was observed in the wear tests performed in water. Ambient scratch tests produced slightly shallower scratch trenches than wet scratches consistently as a function of the varied normal load. Single scan lines provide valuable information about the mechanisms and progression of the nanoscale wear. The different components of scratch friction are investigated to explore the main contributors to the nanoscale scratching of gold.

Dynamic friction, wear volumes and wear morphology have been studied for sliding wear in polysilicon in ambient air at μN normal loads using on-chip micron-scale test specimens. With increasing number of wear cycles, the friction coefficients show two distinct types of behavior: (i) an increase by a factor of two and a half to a steady-state regime after peaking at three times the initial value of about 0.10 ± 0.04, with no failure after millions of cycles; (ii) an increase by a factor larger than three followed by failure after ∼105 cycles. Additionally, the average nano-scale wear coefficient sharply increased in the first ∼105 cycles up to about 10−4 and then decayed by an order of magnitude over the course of several million cycles. For both modes of behavior, abrasive wear is the governing mechanism, the difference being attributed to variations in the local surface morphology (and wear debris) between the sliding surfaces. The oxidation of worn polysilicon surfaces only affects the friction coefficient after periods of inactivity (>30 min).

Accelerated molecular dynamics (MD) simulations of recent Atomic Force Microscope (AFM) experiments on oxidized silicon surfaces demonstrate a nontrivial dependence of frictional force on sliding velocity as well as temperature. By implementing hyper dynamics (HD) via the bond-boost method these simulations achieve sliding velocities in the range of real experimental values. Moreover, an analysis of the effects of temperature and sliding velocity on friction provide evidence for a systematic deviation from the modified Tomlinson model. We hypothesize regarding the origin of these deviations, and use the simulations to analyze the atomic processes that accompany sliding.