A New Method to Evaluate Thin Film Adhesion

This paper discusses a new method of evaluating thin film adhesion both qualitatively and quantitatively via a combination of peeling and image processing techniques. The adhesion of thin film on the entire substrate can be quickly evaluated and quantified to a continuous response variable which is superior to a discrete response variable as described in the ASTM D3359-78 publication. Feasibility of this technique has been demonstrated through a gauge capability study which resulted in 2.7% P/T (precision to tolerance) ratio at six sigma standard deviation for a tolerance of 100. Experimental results using the proposed method to evaluate the process/property relationship of aluminum films as deposited onto various dielectric substrates such as polyimide, silicon dioxide, and silicon nitride have been obtained and have been shown to agree with conventional stud pull test results. The estimated cycle time to evaluate thin film adhesion is five minutes per 4-inch size wafer once the sample is prepared. This short process cycle time and proven reliability show that there is merit in implementing this technique both in the laboratory for process development and in the factory for statistical process control of products.