Long Slender Piezo-Resistive Silicon Microprobes for Fast Measurements of Roughness and Mechanical Properties inside Micro-Holes with Diameters below 100 µm.

During the past decade, piezo-resistive cantilever type silicon microprobes for high-speed roughness measurements inside high-aspect-ratio microstructures, like injection nozzles or critical gas nozzles have been developed. This article summarizes their metrological properties for fast roughness and shape measurements including noise, damping, tip form, tip wear, and probing forces and presents the first results on the measurement of mechanical surface parameters. Due to the small mass of the cantilever microprobes, roughness measurements at very high traverse speeds up to 15 mm/s are possible. At these high scanning speeds, considerable wear of the integrated silicon tips was observed in the past. In this paper, a new tip-testing artefact with rectangular grooves of different width was used to measure this wear and to measure the tip shape, which is needed for morphological filtering of the measured profiles and, thus, for accurate form measurements. To reduce tip wear, the integrated silicon tips were replaced by low-wear spherical diamond tips of a 2 µm radius. Currently, a compact microprobe device with an integrated feed-unit is being developed for high-speed roughness measurements on manufacturing machines. First measurements on sinusoidal artefacts were carried out successfully. Moreover, the first measurements of the elastic modulus of a polymer surface applying the contact resonance measurement principle are presented, which indicates the high potential of these microprobes for simultaneous high-speed roughness and mechanical parameter measurements.

Quantitative wear evaluation of tips based on sharp structures.

To comprehensively study the influence of atomic force microscopy (AFM) scanning parameters on tip wear, a tip wear assessment method based on sharp structures is proposed. This research explored the wear of AFM tips during tapping mode and examined the effects of scanning parameters on estimated tip diameter and surface roughness. The experiment results show that the non-destructive method for measuring tip morphology is highly repeatable. Additionally, a set of principles for optimizing scanning parameters has been proposed. These principles consider both scanning precision and tip wear. To achieve these results, an AFM probe was used to scan sharp structures, precisely acquiring the tip morphology. Tip wear was minimized by employing lower scanning frequency and free amplitude, and a set point of approximately 0.2, resulting in clear, high-quality AFM images.

Assessing the effect of piezoelectric ultrasonic scaler tip wear on root surface roughness under influence of various working parameters: A profilometric and atomic force microscopic study.

Background: Assessing the effect of scaler tip wear on the root surface roughness using piezoelectric ultrasonic scaling device under influence of various working parameters, i.e. power setting, lateral force, and instrumentation time. Materials and Methods: An experimental study was conducted using 160 single-rooted tooth samples divided into two groups of new (n = 80) and worn tips (n = 80). Samples were prepared to examine the root surface roughness after being instrumented by new and worn piezoelectric ultrasonic tips (8 new/8 worn) at different parameters. The erosion ratio (ER) of the new/worn tip was examined under an atomic force microscope and roughness over root surface was measured by a contact surface profilometer. One-way analysis of variance test, post hoc Tukey's test, and independent t-test were used for intragroup, pair-wise multiple comparisons and intergroup comparison of average roughness (Ra) value. Results: A statistically significant difference was found between the ER of new and worn scaler tips (P < 0.001). Intragroup comparison between subgroups 1 and 8 showed a higher Ra value in both the groups (P < 0.005). There was a significantly higher Ra value of worn tips compared to new tips (P < 0.05). Significantly higher mean Ra value was shown when lateral force changed from 50 g to 100 g (P < 0.005). Conclusions: Increasing value of power setting, lateral force, and instrumentation time caused more surface roughness in worn-out scaler tips compared to new scaler tips. Lateral force and instrumentation time proved to be a major factor influencing surface roughness.

Wear comparison of critical dimension-atomic force microscopy tips.

Nanoscale wear affects the performance of atomic force microscopy (AFM)-based measurements for all applications including process control measurements and nanoelectronics characterization. As such, methods to prevent or reduce AFM tip wear is an area of active research. However, most prior work has been on conventional AFMs rather than critical dimension AFM (CD-AFM). Hence, less is known about CD-AFM tip-wear. Given that tip-wear directly affects the accuracy of dimensional measurements, a basic understanding of CD-AFM tip wear is needed. Toward this goal, we evaluated the wear performance of electron beam deposited CD-AFM tips. Using a continuous scanning strategy, we evaluated the overall wear rate and tip lifetime and compared these with those of silicon-based CD-AFM tips. Our data show improved tip lifetime of as much as a factor of five and reduced wear rates of more than 17 times. Such improvements in wear rate means less measurement variability and lower cost.

Tip wear and tip breakage in high-speed atomic force microscopes.

Tip abrasion is a critical issue particularly for high-speed atomic force microscopy (AFM). In this paper, a quantitative investigation on the tip abrasion of diamond-like-carbon (DLC) coated tips in a high-speed metrological large range AFM device has been detailed. Wear tests are conducted on four different surfaces made of silicon, niobium, aluminum and steel. During the tests, different scanning speeds up to 1 mm/s and different vertical load forces up to approximately 33.2 nN are applied. Various tip characterization techniques such as scanning electron microscopy (SEM) and AFM tip characterizers have been jointly applied to measure the tip form change precisely. The experimental results show that tip form changes abruptly rather than progressively, particularly when structures with steep sidewalls were measured. This result indicates the increased tip breakage risk in high-speed AFM measurements. To understand the mechanism of tip breakage, tip-sample interaction is modelled, simulated and experimentally verified. The results indicate that the tip-sample interaction force increases dramatically in measurement scenarios of steep surfaces.

The Effect of Piezoelectric Ultrasonic Scaler Tip Wear on Root Surface Roughness at Different Working Parameters: An Atomic Force Microscopic and Profilometric Study.

OBJECTIVE: This study aimed to evaluate the influence of scaler tip wear and different working parameters, i.e., lateral force, power setting and tip angulation, on the roughness of root surfaces following treatment with piezoelectric ultrasonic scaling devices. MATERIALS: Twenty piezoelectric ultrasonic scaler inserts (10 worn/10 new) were selected to examine the erosion ratio (ER) under atomic force microscopy (AFM). A total of 160 root samples were prepared and instrumented by new (n = 80) and worn inserts (n = 80) at different working parameters (tip angulation, power setting, lateral force). Roughness change (Rc) on root surfaces after instrumentation was examined by a contact profilometer. RESULTS: Statistically significant differences were found between the mean ERs of new and worn tips (p < 0.0001). The various combinations of the assessed working parameters showed synergistic effects resulting in a wide range of root surface roughness. The present study found the higher Rc in the group with a 45° angulation, (P10) high power setting and 1.0 N lateral force (subgroup 8) when compared to other groups. Among the groups, the worn scaler tips subgroup 8 showed a higher Rc (5.692 ± 0.81) when compared to new scaler tips subgroup 8 (4.798 ± 0.51; p < 0.001). CONCLUSION: The findings of the present study highlighted that scaler tip wear strongly influences the root surface roughness when used at higher tip angulation, lateral force and power settings. Hence, ultrasonic scaler tip wear should be periodically evaluated and should be considered as much as the other working parameters.

Study on effects of scan parameters on the image quality and tip wear in AFM tapping mode.

Due to the tip-sample interaction which is the measurement principle of Atomic Force Microscope (AFM), tip wear constantly occurs during scanning. The blunt tip caused by the wear process makes more tip geometry information involved in the image, and correspondingly it increases the measurement error. In the present study, the scan parameters of AFM in tapping mode which affect the wear of single crystal silicon tips, such as the approaching rate, the scan rate, the scan amplitude, and the integral gain are investigated. By proposing a parameter reflecting the imaging quality, the tip state tracing the sample surface is evaluated quantitatively. The influences of scan parameters on this imaging quality parameter are obtained by experiments. Finally, in order to achieve the perfect images with little tip wear influence, tip wear experiments are carried out and then the optimal parameter settings which can lighten the tip wear are obtained.