MRSU SCIENTISTS DEVELOP A METHOD TO CONTROL POROSITY IN THIN METAL FILMS

Scientists at Ogarev Mordovia State University have developed a new method for determining the overall porosity of thin metal films and coatings, potentially improving quality control in modern industrial production.

Thin metal films and coatings are widely used in microelectronics, radio engineering, optics, laser technology, energy and mechanical engineering. Their performance can depend significantly on the presence and distribution of pores within the material.

Pores can be either open, connected to each other and the surrounding environment, or closed, isolated inside the material and therefore difficult to detect using many conventional instruments. Such hidden pores can reduce the thermal and electrical conductivity as well as the strength of metal films and coatings.

The method developed by MRSU researchers makes it possible to determine the overall porosity, including both open and closed pores, within a localized area of a thin metal layer ranging from 1 to 50 micrometres in thickness.

The technique combines two measurements. First, researchers use an optical profilograph to determine the geometric thickness of the metal layer in a localized area. A simple foil mask with a circular opening is placed over the sample, allowing the researchers to measure the surface profiles of both the substrate and the metal layer.

The effective X-ray thickness of the same area is then measured using an X-ray fluorescence thickness gauge. The difference between the geometric and X-ray thicknesses makes it possible to determine the overall porosity of the metal layer.

«By calculating the difference between the surface profile heights of the metal layer and the substrate, we determine the geometric thickness of the thin metal layer in the localized area. We then measure its effective X-ray thickness. The difference between these values allows us to determine the overall porosity,» explained Mikhail Novopoltsev, PhD in Physics and Mathematics, Associate Professor and Leading Researcher at the Department of Physical Materials Science of the Institute of Science-Based Technologies and New Materials at MRSU.

Existing methods for determining overall porosity are primarily designed for bulk materials and cannot be readily applied to thin metal layers deposited on substrates. The MRSU researchers' approach uses an optical profilograph and an X-ray fluorescence thickness gauge, equipment that is often already available at industrial enterprises. This could facilitate the integration of the method into existing production processes without significant additional costs.

The main industrial partner in the project is PJSC Electrovypryamitel. The joint research is focused on practical implementation of the method in the company’s production processes, while the technology can also be used by other manufacturers.

The invention was developed as part of a state-funded research project supported by the Ministry of Science and Higher Education of the Russian Federation (research project code FZRS-2025−0002).