AVS 47th International Symposium
    Thin Films Tuesday Sessions
       Session TF-TuA

Paper TF-TuA9
Quantification of Scratch Resistance and Accelerated Wear for Thin Film Coatings Using the Newly Developed Micro-Tribometer and Testing Procedure

Tuesday, October 3, 2000, 4:40 pm, Room 203

Session: Mechanical Properties of Thin Films
Presenter: C. Gao, Center for Tribology
Authors: C. Gao, Center for Tribology
N. Gitis, Center for Tribology
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Quantification of scratch and accelerated wear resistance of thin films ranging from 1 nm to 1000 nm was achieved by using critical loads, at which the given films were progressively worn through. Progressive worn through of thin carbon films (3 nm to 8 nm) on magnetic disks using a micro-blade under precision motion with linearly increasing loads from 0.2 grams up to 400 grams was clearly observed simultaneously from electrical contact resistance (ECR), friction force and acoustic emission (AE) signals. At the critical load, friction force and AE fluctuated violently and ECR dropped to practically zero. The critical load was found to increase with increasing carbon thickness, as expected. The wear depths at the critical loads were measured post-test using Tencor profiler and optical surface reflection and found to be in excellent agreement with film thickness. A lubricant film as thin as 1 nm on the carbon films enhanced the critical load by a factor of five to ten. The same testing procedure was applied for thicker diamond-like carbon films on silicon substrate ranging from 50 nm up to 1000 nm, but with linearly increasing loading force from 0.2 N up to 40 N. Good correlation was found between critical load and film thickness, and also between critical load and residue film stress also. However, there was no correlation between critical load and nano-hardness. We believe that the nanohardness measurements may not apply for films thinner the sub-micrometer, since the contact stress distributed well into the substrate when nano indentation was made. The successful quantification of scratch resistance and accelerated wear is attributed to precision motion, linearly increasing load mechanism and the contact geometry of the micro-blade. The micro-blade will be described and the mechanism for its effectiveness on surface film evaluations will be discussed, as compared to much less effective counter surfaces, such as a diamond stylus or a stainless steel ball.