Computational Design and Optimisation of Mechanically Reinforced Masks for Stencil Lithography

Identifying, predicting and optimising stencil lithography is critical to the successful and timely development of this technique with a wide range of potential applications such as deposition on non- conventional and unstable materials (i.e. bio-chemical, hydrophobic), patterning heterostructures (epitaxial, magnetic, complex oxides, piezoelectric materials) and deposition of nanodevices onto CMOS. Previously confirmed for cantilever-like stencils is the thesis that degrading effects of stress-induced deformation of stencils can be overcome by strategic placement of corrugating structures. This approach is further exploited in this work to mechanically stabilise complex stencil designs. This involved studying the evolution of stencil deformation due to deposition induced stress and iterative design of optimal corrugation structures to be incorporated into the stencils. It is shown that degrading effects of stress-induced deformation of stencils can be significantly reduced which subsequently improves pattern definition. Reduction in deformation and in pattern distortion in the range of 50% to 96% was achieved.