Nanoscale surface measurements at sidewalls of nano- and micro-structures

Abstract

A method for direct and non-destructive sidewall scanning of nano- and micro-structures is presented. The measurements are performed with a kind of novel ‘assembled cantilever probe (ACP)’. Such ACPs consist of four parts: substrate, cantilever, extension(s) and probe tip(s). The tip(s) located at the free end of the extension may extend horizontally. As a benefit, the ACPs are capable of probing in a direction perpendicular to sidewalls. The bending, torsion or deformation of the cantilever is detected when the tip is brought into contact, intermittent contact or non-contact, with sidewalls. Investigations show that the ACPs have a low measurement noise at a subnanometre level. Measurement examples performed at the sidewalls of microtrenches, microgears and line edge roughness samples are given in this paper.

Sensitivity and resonant frequency of an AFM with sidewall and top-surface probes for both flexural and torsional modes

“…It takes approximately 20-30 min in order to fabricate this kind of ACP [26]. The geometrical parameters and configuration of this ACP are depicted in Fig.…”

“…Kahrobaiyan et al [25] derived a closed-form solution for the torsional resonant frequencies and torsional sensitivities of this kind of AFM probes and assessed the influence of the ratio of the vertical extension length to the horizontal cantilever length on the torsional resonant frequencies and of course torsional sensitivities. Dai et al [26] also proposed a new assembled cantilever probe, which is used for simultaneous scanning of faces and sidewalls of microstructures especially microgears in the same coordinate. This simultaneous scanning provides a facility to decrease the time of scanning, which leads to a swift topography process.…”

Direct Measurement of Three-Dimensional Forces in Atomic Force Microscopy

“…(9) can be used along with (8) to obtain σ f x , σ f y , and σ f z as functions ofỹ 1 = y 1 / ,ỹ 2 = y 2 / , and are given by…”

“…This is because the AFM probe possesses maximum sensitivity to tipsample forces along the Z-axis. Increasingly, however, the AFM is being employed in applications that require interacting with inclined surfaces and three-dimensional (3-D) features, such as in the metrology of trenches and side walls of microfabricated parts [9]- [11] and in manipulation of nanoparticles [12]- [16]. In these applications, where the tip-sample interaction force possesses components along all the three axes, the performance of the AFM is rendered suboptimal for two reasons: First, conventional measurement systems measure components of forces at most along two independent axes.…”

Resonant Frequency and Sensitivity of a Caliper Formed With Assembled Cantilever Probes Based on the Modified Strain Gradient Theory

“…In order to overcome the limitations of conventional AFMs, Dai et al (2006Dai et al ( , 2007 proposed assembled cantilever probes (ACPs) for direct and nondestructive sidewall measurement of nano-and microstructures. Unfortunately, the probe tip never comes in to close proximity to sidewalls, no matter how sharp and thin the tips are.…”