Study On High-Density Ferroelectric Nanodots By Electron Beam Lithography And Their Performance Of Data Storage

Ferroelectric materials are a typical dielectric material.They usually shows excellent ferroelectricity,piezoelectricity and pyroelectricity due to spontaneous polarization dipoles.The direction of the spontaneous polarization dipoles can be switched under the action of external electric field.The most representative one is organic ferroelectric material,such as P（VDF-TrFE）,which has good ferroelectricity,piezoelectricity and pyroelectricity,etc.It shows great potential for applications in non-volatile memory,piezoelectric/thermoelectric sensing arrays and other organic electronic devices.Remarkably the preparation of different scales of micro and nano structures is widely used in modern electronic industry.However,with the rapid development of micro and nano devices,there is a lack of effective means for the preparation and realization of micro and nano functionalization of organic ferroelectric materials.In this paper,the effect of different electron beam doses on the film were investigated in the dose test experiments.It was found that N-N-dimethylformamide（DMF）was the better development for nanodots than that of butanone.A high-density P（VDF-TrFE）nanodots with a 400 nm period were prepared by electron beam lithography technology.Moreover,the multi-dimensional ferroelectric rose patterns were also prepared.High-resolution patterning of ferroelectric nanostructures with high piezoresponse is the key issue for developing ferroelectric memory（Fe RAM）and encryption.For the organic ferroelectric material P（VDF-TrFE）（70:30）,when the electron beam irradiation dose was 24μC/cm²,the effect of electron beam doses on crystal structure were identified by the X-ray diffraction and Fourier transform infrared spectroscopy.The crystal structure was transferred from ferroelectric crystals with all-trans TTTT conformation into relaxor ferroelectric crystals with TGTG’,TTTGTTTTG’or T_n>=4G conformation,which resulted in the excellent data storage behavior in the P（VDF-TrFE）.We found that the ring writing speed of the irradiated P（VDF-TrFE）film was up to 2000 times,which was higher than that of the unirradiated P（VDF-TrFE）film.And 2-fold reduction of power consuming was achieved in irradiated P（VDF-TrFE）crystals compared with normal ferroelectric P（VDF-TrFE）.Finally,two inputs method,electron beam and electric field,were used to change the dipe direction and write the data in the irradiated P（VDF-TrFE）.And the multiplexing memory is capable of both electron-beam write-only-memory（EB-WOM）as digital watermarking and high-security-level Fe RAM for data storage and encryption.Furthermore,the effect of different electron beam doses on the film were investigated in the dose test experiments.It was found that butanone was the better development for nanodots than that of N-N-dimethylformamide.A high-density P（VDF-TrFE）nanodots and nanowires with a 200 nm period were prepared by electron beam lithography technology.This paves the way for further study of P（VDF-TrFE-CTFE）film in micro-nano electronic and information storage.In summary,we have developed a direct writing patterning-electron beam lithography technique to prepare ferroelectric nanostructures on the surface of ferroelectric copolymer films,and for the first time,the data storage behavior of irradiated nanopatterns were achieved using piezoelectric force microscopy.