Numerical simulation was performed on a new high resolution micro-lithography using thermo-resist. This high resolution optical-thermal lithography uses a thermo-resist instead of photoresist taking advantage of a nonlinear superposition effect. The nonlinear superposition utilizes the fact that thermo-resists do not follow the reciprocity law. This phenomena allows to separate a complex image into simple sub-sets which are imaged onto the same die. This concept will realize a fabrication of 100nm features with existing steppers and without and proximity effects. Hopkin's 4D integral is used for calculations of the diffraction intensity of projection image. Intensity of impressed heat flux is assumed to be proportional to the intensity of this diffraction image. Transient heat transfer in wafer and layer of thermo-resist is analyzed by non-linear 3D finite element method. The numerical result demonstrates a drastic improvement in resolution that can be obtained with conventional method using photo-resist.
"Numerical analysis of high-resolution microlithography with thermoresist", Proc. SPIE 3676, Emerging Lithographic Technologies III, (25 June 1999); doi: 10.1117/12.351109; https://doi.org/10.1117/12.351109