"Sketch And Peel" Lithography And Its Applications

Charged-particle beam patterning,which takes electron-beam lithography(EBL)and focused ion beam(FIB)as the core,plays the important role in the field of chip making,photomask manufacturing and repairing,process metrology,because of the high-resolution fabrication of original patterns.Meanwhile,its capability of high-resolution flexible patterning provides an excellent reserch platform of fundamental physical fields such as nanoelectronics,nanooptics,high-density magnetic data storage,nanoscale thermal transport and nanoscale mechanism.With the development of fundamental studying,charged-particle beam patterning process encounter the tough issues such as low efficency in patterning and challenging in the fabrication of high-fidelity structure.Hence,faster and higher-resolution patterning based on charged particle beam is the key role in the studying of nanofabrication.This dissertation reports a novel patterning process,named "Sketch and Peel"lithography,which not only largely improve the efficiency of patterning and extend the applicable fields of charged particle beam patterning."Sketch and Peel" lithography just requires to defines the outline of target patterns with charged particle beam,which maximally mitigates the proximity effect in EBL process and inevitable redeposition in ion beam milling and boosts the development of charged particle beam patterning.The quintessence of "Sketch and Peel" lithography is that sketch outline templates of target patterns by charged particle beam,selectively strip away the metallic film ouside outline and finally achieve the patterning of design metallic structures.Through systemic control experiments,we clarify that the basic principle of selective stripping,which is ascribed to defined outline by charged particle beam avoid the initial breakage the metal-substrate interface inside outline and have high stability of mechanism.When peeled off metallic film outside outline,metallic structure can be confined in outline and present selective stripping.To boost the novel patterning process,we get a deep insight into "Sketch and Peel"lithography based on EBL and FIB milling.The main contents are list as follow:(1)Electron beam "Sketch and Peel" lithography not only improve the patterning efficiency of electron beam direct writing with hundred times,and also achieve the rapid and reliable high-fidelity patterning.Through systemic control experiments,we know "Sketch and Peel" lithography can cover the fabrication requirement of several-ten-nanometer microscopic structure to sub-millimeter-scale macroscopic patterns.With the optimal pattern design of shared boundary,electron beam "Sketch and Peel" lithography can achieve the rapid fabrication nanogaps in multiscale patterns.As a demonstration,we the define gold nanobowtie array having uniform gap of?15 nm,and the dark-field and Raman meansurement show that the pronounced coupling-induced redshift of resonated energy and near-field enhancement in such small metallic gap.(2)Focused ion beam based "Sketch and Peel" strategy not only figure out the tough issue of low patterning efficiency using FIB milling,and also avoid large-area substrate damage from high-energy ion bombardment which deteriorate the performance of optical and electronic properties.Especially,"Sketch and Peel" strategy enable He+-FIB milling to be practical and most advanced multiscale patterning tool with extreme high resolution,which extend the applicable fields of He+-FIB patterning.In addition,we utilize He+-FIB milling based on "Sketch and Peel" lithography to define gold nanodisk dimer with 15-nm gap which present obvious plasmonic coupling modulated resonated energy.(3)The high-quality fabrication of nanogaps based on "Sketch and Peel" lithography is quite appropriate method to study plasmonic strong coupling and non-linear effect.We demonstrate split nanodisk with ultrathin nanoslit fabricated by electron beam "Sketch and Peel" lithography exhibits pronouced plasmonic strong coupling-induced Fano resonance.The intensity and energy of Fano resonance can be tuned by varied geometric parameters of split disk defined by high-quality fabrication of "Sketch and Peel" lithography.Meanwhile,the narrow and uniform gap in split disk generate the extremely high field enhancement and intensive second harmonic generatrion.(4)Based on the high resolution property of HSQ in EBL process,we demonstrate large-area and unifrom sub-20-nm gaps defined by electron beam "Sketch and Peel"lithography,the rapid fabrication process to obtain high-density metallic nanogaps provide a reliable method to the preparation of high-sensitivity SERS substrate.We also develop the PMMA-based dry lift-off process which originated from the patterning strategy of confinement in "Sketch and Peel" lithography,which can fabricate low-damping plasmonic nanostructures and have lower dissipiation of resonance and stronger field enhancement.The dissertation systemically demonstrates the basic principle,process limit and design rule of "Sketch and Peel" lithography based on electron beam and focused ion beam,which not only innovate the thought of charged particle beam fabrication,and is of great significance to the development of charged particle beam patterning.