Review of material measures for surface topography instrument calibration and performance verification

Abstract

As the need for the manufacturing of complex surface topographies increases, traceable measurement with known uncertainties can allow a manufacturing process to remain stable. Material measures are the link in the chain that connects the surface topography measurement instrument’s output to the definition of the metre. In this review, the use of material measures is examined for the purposes of instrument calibration and performance verification based on the metrological characteristics framework, as introduced in ISO 25178 part 600. The material measures associated with each metrological characteristic are investigated in terms of fabrication, geometry and functionality. Material measures for metrological characteristics are discussed in a sequential approach, focusing on material measures that have been developed for specific measurement technologies and optical surface topography measurement instruments. There remains a gap in the metrological characteristic framework for the characteristic, topography fidelity, and the review highlights current methods using reference metrology and alternative approaches using virtual instruments to quantify the effects of topography fidelity. The influence of primary instruments is also reviewed in the context of uncertainty propagation. In the conclusion, the current challenges are identified with regards to the scarcity of available material measures in the lower nanometre range, and the limitations in terms of cost, complexity, manufacturing time and industrial applicability.

Linearizing the vertical scale of an interferometric microscope and its effect on step-height measurement

“…In normal CSI mode, the filter and aperture are removed. The centroid wavelength of the light passing through the objective is measured with a spectrometer referenced to the 546.075(1) nm Hg spectral line and found to be 547.090 (10) nm [22]. (Throughout this paper, numbers in parentheses represent standard uncertainties with 68% confidence intervals and refer to the corresponding last digits in the result.)…”

“…In all scanning microscopes, the displacement of the scanning stage, typically a piezoelectric stage, needs to be known, and calibration is required to ensure the traceability of measurements to the SI meter. Calibration of the linear component, the amplification coefficient [8][9][10], is often performed using a calibrated physical artifact, typically a step-height standard. De Groot and Beverage proposed a method for performing an absolute calibration of the amplification coefficient for interferometric microscopes that does not require a step-height standard [11].…”

“…The linearity deviation is then obtained as the maximum observed deviation of the step height measurement values to their respective calibrated values, after compensation for the estimated error in the vertical axis amplification coefficient. Artifacts representing different step heights, or artifacts incorporating a staircase of heights, can be used to estimate the actual instrument response curve that describes the relation between measured and nominal relative surface heights [10,13,14]. Kiyono et al [15] describe an alternative approach that involves stepping a step height artifact though the scanning range.…”

Step height measurement of monoatomic silicon crystal lattice steps with a commercial atomic force microscope

“…Typically, SPMs are calibrated using transfer standard artefacts fabricated with well-defined silicon structures, using common microelectronics industry fabrication techniques [4,5]. These structures include pitch gratings for calibrating an instrument's X/Y-axes (horizontal, in-plane axes), step heights for calibrating an instrument's Z-axis (vertical, outof-plane axis) and individual line and groove structures for critical dimension validation and calibration.…”