Ž . Diamond and Related Materials 10 2001 9498 Intrinsic stress measured on ultra-thin amorphous carbon films deposited on AFM cantilevers P. Lemoine  , J.F. Zhao, A. Bell, P. Maguire, J. McLaughlin NIBEC, School of Electrical and Mechanical Engineering, Uni  ersity of Ulster at Jordanstown, Shore road, Newtonabbey, Co. Antrim BT37 OQB, Northern Ireland, UK Received 28 June 2000; accepted 11 October 2000 Abstract Ultra-thin amorphous carbon films were deposited onto atomic force cantilevers by plasma enhanced chemical vapour deposition. High magnification scanning electron micrographs at 30 kV reveal that the AFM tip is not affected by the deposition but its radius is broadened by the presence of the coating. Energy dispersive X-ray analysis at 4 kV shows that the film mostly coats one side of the lever, resulting in a bending of the cantilever, readily observable by scanning electron microscopy. This deformation is elastic and is caused by an internal compressive stress of 2.60 and 2.54 GPa, respectively, for 20-nm and 110-nm-thick films. After 15 at.% Si incorporation, these stresses are reduced to 0.97 and 0.78 GPa. It is believed that the increased hydrogenation upon silicon addition causes a loosening of the carbon network structure and is, therefore, responsible for the observed stress relief.  2001 Elsevier Science B.V. All rights reserved. Keywords: Amorphous carbon; AFM cantilever; Compressive stresses; Ultra-thin films 1. Introduction Ž . Diamond-like carbon DLC presents properties in- termediate between those of diamond and graphite and can be used for applications requiring hard, inert and durable coatings. Smooth films can be deposited at room temperature by various plasma deposition tech-  niques 1 but in most cases, the films grows under a compressive stress and this seriously limits tribological  applications for DLC. Stress relief by annealing 2 , ion    bombardment 3 , silicon 4 and nitrogen 5 atom incorporation has been observed but is often followed by a degradation of the mechanical properties. A com- mon interpretation is that these internal stresses are  Corresponding author. Tel.: 44-1232-386-940; fax: 44-1232- 366-863. Ž . E-mail address: p.lemoine@ulst.ac.uk P. Lemoine . due to the incorporation of gaseous species or the displacement of substrate atoms. They develop through a microstructural evolution of the film, which is inti- mately linked to the deposition process of hard DLC  films 6 . However, thick stress-free amorphous-tetra- hedral carbon films with hardness near that of diamond  have also been reported 2 . Therefore, the origin of these stresses is incompletely understood. Thin film stresses are measured by estimating the bending of the coated substrate using contact profilers  or optical techniques 7. These measurements are based upon the observations of G.G. Stoney who mea- sured the tension of metallic films deposited by elec-  trolysis 8 . The stress  under which the film is de- posited is given by; E t 2 1 1 s s Ž.    1 ž / t R R Ž . 61   f 0 s 0925-963501$ - see front matter  2001 Elsevier Science B.V. All rights reserved. Ž . PII: S 0 9 2 5 - 9 6 3 5 00 00455-6