The effect of film thickness on the tribomechanical properties of the chrome-gold thin film

This paper reports on the tribo-mechanical properties of Si/SiO₂/Cr/Au thin films with different thickness. We concentrated on Cr/Au films since this alloy in bulk is known as a stable low resistance material. Due to their superior tribological properties, Cr/Au thin films have offered opportunities in many technical applications, such as protective coatings and wear-resistant coatings. Recently, the passivation of silicon surfaces within microelectromechanical systems (MEMS) using Cr/Au thin films has been proposed to prevent stiction and to reduce friction. A full understanding of the tribological and mechanical behavior of thin film is an essential issue in such applications which used the optical sensors or other settings where good adhesion of gold to a substrate is of importance and where controlled topography/roughness is the key. The structural and surface morphology, adhesion, friction, Young's modulus and hardness of this thin film were studied for three different thicknesses. The variation of the film thickness affects the structure, surface and mechanical properties of Cr/Au thin films. Elastic modulus and hardness are two important mechanical properties of the thin-film structural materials used in microelectromechanical systems. The mechanical properties of electroplated chrome-gold thin film are found to be highly dependent on the manufacturing process and also on the thin film thickness.