How the thickness of molybdenum films influences their properties.

What influence does the thickness of molybdenum films have on their properties? The Faculty of Functional Materials at the Montan University in Leoben teamed up with Plansee to investigate this question in detail.

And they found that grain size grows as the thickness of the film increases. However, resistivity and stress remain constant as of a film thickness of 1 µm.

Molybdenum films are used in thin-film transistors for TFT LCD screens and in thin-film solar cells, for example. Its low coefficient of thermal expansion, high chemical and thermal stability and good electrical conductivity make molybdenum an ideal choice for producing conductive films on glass.

Previous studies have analyzed how different deposition processes affect the molybdenum film. The influence of the thickness on the film properties had not been investigated. So the Montanuniversität Leoben looked at molybdenum film layer growth in detail. At the beginning of the growth process, small crystallites with two different orientations are formed. These are designated (110) and (211). As growth of the film continues, the size of the (110)-oriented domains grows up to 300 nm, whereas the (211)-oriented crystallites barely change in size. Variation of the stress in the film relative to the film thickness was also investigated. This ceases to change with a thickness of 1 µm and remains constant at around -200 MPa. As of this thickness, the conductivity does not change significantly either.

Would you like to read more? The detailed findings can be found in the paper Sputtered molybdenum films: Structure and property evolution with film thickness, (Vacuum, Vol. 99, 2014, 149-152.) published by Elsevier.