Sub-diffraction-limit Lithography Based On Surface Plasmon Polaritons

Photolithography is the most used technique for fabricating large-area integratedphotoelectric devices. However, the conventional photolithography techniques have beenunable to meet the demand of fabricating ultrahigh-density integrated devices because theirresolutions cannot go beyond the diffraction limit. To address this problem, this thesisfocuses on developing sub-diffraction-limit photolithography techniques based on surfaceplasmon polaritons. The research content includes surface plasmon interference lithography,superlens imaging lithography and optical beam direct writing photolithogaphy. The mainresults are shown as follows:1. A surface plasmon interference lithography method (SPILM) was proposed.Simulation results show that this SPILM can produce periodic patterns with ahalf-pitch resolution of28.2nm under248nm illumination. This SPILM can use amask with a low resolution to produce a large-area pattern with a resolution beyondthe diffraction limit.2. A unidirectional surface plasmon generator (USPG) based on groove-slit structureswas designed, and a SPILM with designed USPGs was proposed. Simulation resultsshow that this SPILM can produce periodic patterns with a half-pitch resolution ofabout49.4nm under365nm illumination, and the area of producing the periodicpatterns can be controlled by changing the distance between two used USPGs. ThisSPILM can selectively produce periodic patterns in the desired area.3. A deep ultraviolet coupled surface plasmon interference lithography method(DUCSPILM) was proposed. Simulation results show that this DUCSPILM canproduce periodic patterns with a half-pitch resolution of14.6nm under193nmillumination. It was found that if a high-refractive-index photoresist with a refractiveindex of1.8is used, the half-pitch resolution of the patterns produced by thisDUCSPILM can reach12.9nm. This DUCSPILM is the first to break15nm half-pitchresolution. This work opens up an avenue to push the half-pitch resolution of photolithography below13nm.4. A method for enhancing the performance of the metal superlens imaging lithographywas proposed. Simulation results show that this method can enhance the workingdistance of the metal superlens and improve the quality of sub-diffraction-limitpatterns produced in the photoresist at the same time.5. A metal-superlens-hyperlens imaging lithography method (MSHILM) was proposed.Simulation results show that this MSHILM can produce patterns with a half-pitchresolution of about36nm and a reduction factor of2.2under365nm illumination. ThisMSHILM can use a mask with a low resolution to produce sub-diffraction-limitpatterns because sub-diffraction-limit demagnification imaging lithography can beperformed by this MSHILM.6. A metal lens based on two nanobars was designed, and an optical beam direct writinglithography method (OBDWLM) with this designed metal lens was proposed.Simulation results show that under365nm illumination, this OBDWLM can produce apattern with a feature size below180nm in a photoresist which is50nm away from thedesigned metal lens. Because this OBDWLM is a non-contact maskless lithographymethod, it can overcome the difficulty of fabricating high-resolution masks.7. A metal lens based on spatial multiplexing gratings was designed, and an OBDWLMwith this designed metal lens was proposed. Simulation results show that under365nm illumination, this OBDWLM can produce a pattern with a feature size of about230nm in a photoresist which is1μm away from the designed metal lens. ThisOBDWLM can produce a high resolution pattern in a photoresist which is far awayfrom the designed metal lens due to the long focal length of the designed metal lens.