Lasers set to stun with advanced surface analysis

Today highly developed techniques are available for chemically analysing surface regions with thickness of few atom layers, but mechanically testing thin and ultra-thin films is still a challenge. This challenge is increasing with the current development of films of higher hardness and reducing thickness. Mechanically testing thin films and coatings is highly desirable. Thin films are used for wear protection, saving material resources and reducing costs. The stable and reliable operation of the layer-structures in sensors, micro-chips, projections masks etc. requires to adjust carefully the mechanical properties of the layer-substrate-composite. This needs the knowledge of the material parameters involved. The few mechanical test techniques for thin films are confronted with manifold new demands of the surface engineering and the thin film technology. For example, the permanently increasing bit density of computer hard disks requires the distance between the write-read head and the hard disk to reduce to few ten nanometers. Avoiding damages of the disk is ensured by a super-hard film of only few nanometers thickness. Such films of high performance are deposited from extreme physical conditions as high energy plasma with controlled particle energy spectrum and excellent homogeneity. This suggests the need of quick mechanical test methods supporting the technological development and enabling the production process to be controlled. The laser-acoustic technique is a new method for testing thin films and surfaces that can claim some important advantages as to be non-destructive, easy to use, comparably quick and to be able to test film with thickness down to less than ten nanometers. Film or substrate material can have hardness and stiffness up to the diamond quality.