In situ measurement of stresses in diamond-like carbon films

摘要

In situ determination of streses in thin films can be used as an important tool to assist process development as well as to understand the thermodynamics of film formation.A simple technique for the measurement of stresses in growing films is described here.The technique consists of measuring the displacement of a laser beam reflected from the films surface.Displacement is induced by chanages in the radius of the curvature of the substrate sesulting from stresses in the film.The detector sensitivity at the used vavelength (635 nm)is approximately 12 mV mum~-1,for which our experimental set-up is equivalent to 4 mV murad~-1.The actual data collected consist of the reflected beam displacement vs.time,and provides at any instaant the value of the average stress.By knowing the deposition rate,tiem is directly correlated with film thickness,and the local stress and be determined.Examples of measurement of stresses in teragonally bonded amorphous carbon films prepared by filtered cathodic are are presented,as well as how this technique can be used to design the deposition process to virtualy eliminate intrinsic stresses.