The Thermal Annealing Effect On The Residual Stress And Interface Adhesion In The Compressive Stressed DLC Film.
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U11.42.1
The Thermal Annealing Effect On The Residual Stress And Interface Adhesion In The Compressive Stressed DLC Film.
Heon Woong Choi1, Myoung-Woon Moon1, Tae-Young Kim1,2, Kwang-Ryeol Lee2, and Kyu Hwan Oh1, 1 School of Materials Science and Engineering, Seoul National University, Seoul 151-742, Korea 2 Thin Film Technology Research Center, Korea Institute of Science and Technology, P.O.Box 131, Cheongryang, Seoul 136-791, Korea
ABSTRACT
We studied on the thermal annealing effect on the residual stress and the mechanical properties in thin compressive stressed diamond-like carbon film on Si substrate. Annealing experiments were carried out with Rapid Thermal Procedure system at 200-600 °C, and the stress change with annealing temperature was investigated by in-situ stress measurement system. The apparent stress reduction occurred with minimal structure changes. In order to measure the change of chemical structure of diamond-like carbon film by annealing, we used Raman spectrometer. The adhesion deterioration in interface has been detected as annealing temperature increased. In the compressive stressed DLC film, we observed the dramatic evolution of interface delamination at certain high temperature using in-situ heating stage built in Environment SEM. The quantitative change of adhesion affected by annealing process was also measured with scratch testing. For exploring the interface structure affected by the thermal annealing process at high temperature, the cross section of annealed film has been observed with HR TEM. Keywords: Thermal annealing, Adhesion, Residual stress
INTRODUCTION
Diamond-like carbon (DLC) film has been a candidate for various applications due to its excellent tribological and mechanical properties. The extraordinary combination of high hardness, optical transparency, low coefficient of friction, chemical inertness and high electrical resistivity have stimulated for various applications. However, poor adhesion on most of the substrates limits the practical applications of the DLC films. This poor adhesion is mainly owing to high intrinsic compressive stress which prevents the growth of thick films. High residual compressive stress of the films will be a weak point of DLC films if the DLC films are being employed as wearresistant protective coatings for electronic components, hard disk and machining drills. Therefore it is extremely important to reduce residual stress in the compressive stressed DLC films. Numerous researches suggested that multilayer [1], incorporating metals [2], silicon [3] or thermal annealing [4-7] are practical method to improve the film property. But, metal incorporation has drawbacks such as removing the optical transparency of film. And in case of doped DLC such as Ni, W and Ti also has an improvement of film’s property but also reduction
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Fig. 1. The observation of delamination between the substrate and film during annealing under in-situ. (a) at 400°C (b) at 406°C (c) at 409°C (d) at 410°C (e) at 412°C (f) at 415°C in coating wear resistance [8,
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