3D characterization of printed structures by stylus- and optical-based measurements

Highly-parallel manufacturing is as revolutionary method for large area devices production with sub-micrometre scale features and/or structured surfaces. Nowadays, many devices are available by these fabrication processes, with the subsequent need to improve either in-line and off-line sampling-based controls. Among others, morphological characterizations and resistance measurements are often used for quality control of printed conductors, which features are simple lines or more complex structures. This study, performed on printed linear conductors deposited on flexible plastic sheets made by roll-to-roll process, exploit stylus and optical profilometers for the 3D surface characterization. A more accurate 3D reconstruction of the surface morphology was achieved by the stylus profiler; starting from these topographical measurements, the calculated resistance of selected lines has been compared to resistance measurements by electrical setup. In this work, morphology and roughness parameters of surfaces are characterized using specialized software tools (Mountains Map and SPIP). Resistance measurements are performed with the aim of identifying correlation between critical sizes/forms and functional features. A good repeatability of parameters together with some drawbacks and limitations due to probe size, shape, type of substrate and sampling time are highligthed. An uncertainty budget is estimated for each of the critical sizes and functional feature of the sample structures under test. Meanwhile, the development of application-oriented material measures to support traceability of quantitative measurements of function-correlated parameters is discussed.