This Small Business Innovation Research Phase I project will seek to deposit functionally gradient material (FGM) ceramic coatings on aluminum susceptor materials to encapsulate the susceptor and prevent contamination of silicon wafers during fabrication. Aluminum/aluminum nitride FGM coatings, which are 100% Al at the substrate interface and 100% AlN on the exposed surface with a gradual transition between the two extremes, will be deposited using an ion beam assisted deposition (IBAD). IBAD is a unique process which combines evaporation with concurrent ion beam bombardment to controllably produce ultra-adherent thin films with excellent control over film structure and chemistry. The AlN coating layer will act as a diffusion barrier to eliminate aluminum contamination in high-temperature semiconductor fabrication. The graded nature of the coating will reduce interfacial delamination and facilitate a gradual shift of the thermal expansion coefficient, thus reducing the probability of failures associated with thermal expansion mismatch and increasing the working lifetime of the coating. In Phase I, coating conditions will be varied to produce Al/AlN FGM coatings on sample coupons of Al. Analytical evaluation and thermal cycle performance testing will be used as feedback for additional processing parameter development and coating optimization. Phase I will produce an adherent, durable FGM coating which withstands thermal cycling. The project will also provide analytical data about coating chemistry and coating structures for further parameter optimization in Phase II.
