Atomic Force Microscopy Study of Micrometric Pattern Replica by Hot Embossing Lithography

Strong PolyMethylMetAcrilate (PMMA) resist recoveries, occurring in the centre of micro-scale structures replicated by hot embossing lithography (HEL), have been evidenced after the de-moulding stage. A statistical study by atomic force microscopy clearly reveals that, for a fixed pattern size, the heights and the widths of these recoveries decrease when the imprint temperature goes up and increase with the imprint force up to a critical value before vanishing. It also shows that these resist recoveries increase with the pattern size. This phenomenon is explained qualitatively and quantitatively as a relaxation, during the de-moulding stage, of the elastic stresses stored by the PMMA resist which could not flow during the imprint stage.