177 results about "Reactive-ion etching" patented technology

The invention relates to the field of optical lens coatings, and particularly discloses a preparation method of an antifouling and antibacterial spectacle lens coating. The preparation method of the antifouling and antibacterial spectacle lens coating comprises the following steps: depositing a silicon dioxide substrate on the surface of a lens through plasma enhanced chemical vapor deposition treatment; the preparation method comprises the following steps: dispersing nano-graphene and nano-silver particles in an ethanol solvent, adding a silane coupling agent to form a homogeneous suspension, loading the suspension on the surface of a silicon dioxide substrate through a spin-coating method, and carrying out heat treatment curing to form an antibacterial layer, with the loading amount of nano-silver being less than or equal to 0.5 wt%; and etching the surface of the antibacterial layer by adopting a reactive ion etching method, and then grafting perfluorooctyltriethoxysilane on the etched surface at 80-100 DEG C by adopting a vapor deposition method to form the hydrophobic layer. The preparation method of the antifouling and antibacterial spectacle lens coating has the advantages of being antibacterial, antifouling and high in durability.

The invention provides a TEM sample and a preparation method and application thereof.According to the preparation method of the TEM sample, on the premise that the hole structure of a semiconductor device is not affected, part of residual polymer accumulated and blocked in a hole opening in the semiconductor device is removed through reactive ion etching, so that the hole opening is expanded and not blocked any more; a protective colloid can enter a pore structure for filling and precursor material plating of atomic layer deposition is facilitated, the definition of the side wall of the pore is enhanced, and the quality and the final observation effect of the TEM sample are effectively improved; the equipment and technology adopted by the preparation method of the TEM sample provided by the invention are low in investment, and the operation process is simpler and faster than that of a Fab etching process; meanwhile, batch laboratory-scale sample treatment can also be realized; in addition, compared with a wet chemical corrosion cleaning technology for removing residual polymers, the problems of chemical reagent residues, chemical reactant pollution and the like at the bottom of the deep hole structure are avoided.

The invention relates to a method for transferring a wafer-size two-dimensional semiconductor film through a selenium-assisted dry method, and belongs to the technical field of semiconductors. The method comprises the following steps: sequentially preparing a Se nano layer, a supporting layer and a water-soluble glue layer on a two-dimensional semiconductor film wafer containing a growth substrate; stripping the two-dimensional semiconductor film, the Se nano layer and the supporting layer from the growth substrate together by using a water-soluble glue layer, and then adhering the two-dimensional semiconductor film to a target substrate by taking the two-dimensional semiconductor film as an adhering surface; soaking in water to remove the water-soluble adhesive layer; and removing the support layer through reactive ion etching, and finally performing annealing treatment in an inert gas atmosphere to remove the Se nano layer, thereby obtaining the two-dimensional semiconductor film on the target substrate, and completing the transfer of the two-dimensional semiconductor film from the growth substrate to the target substrate. According to the invention, the wrinkle-free, residue-free and pollution-free high-quality complete cleaning transfer of the wafer-size two-dimensional semiconductor film can be effectively realized.

The invention belongs to the field of micro-nano structures, and relates to a preparation method of a nano needle tip split ring 3D structure periodic array. According to the method, after a reflecting layer and a supporting layer are deposited on a silicon substrate, polystyrene nanospheres are self-assembled, the volume of the nanospheres is reduced through reactive ion etching, then two times of inclined magnetron sputtering are carried out, deposited precious metal is etched through a reactive ion etching machine, and the silicon substrate is obtained. And removing the nanosphere mask to obtain the 3D structure periodic array of the nanotip split ring. The method has the characteristics of simple preparation process, good uniformity, high order degree and strong repeatability, and has wide application potential in the fields of SERS (Surface Enhanced Raman Scattering), photoelectric property detection and the like.

The invention belongs to the field of micro-nano structures, and relates to a preparation method of a single-layer disc 3D structure based on nano needle tip support. According to the method, the single-layer disc 3D structure supported by the nanometer needle tip is obtained through an electron beam thermal evaporation system, a self-assembly technology and reactive ion etching, the preparation process is simple, cost is low, repeatability is good, structural stability is good, and tolerance is high. Compared with a metasurface supported by a silicon substrate, the metasurface provided by the invention has the advantages that the transient signal oscillation modulation capability of the metasurface is greatly improved by the needle point support, the opto-mechanical conversion efficiency and the oscillation quality are remarkably improved, and the quality factor is improved by several orders of magnitude compared with that of a common silicon substrate.

The invention relates to the technical field of optical devices, and particularly discloses a preparation method of an electrostatic drive MEMS Fabry-Perot filter, an SOI wafer is used as a first substrate, top silicon of the SOI wafer is used as a drive structure of the MEMS Fabry-Perot filter, the thickness and mechanical characteristics of a cantilever can be accurately adjusted, and the MEMS Fabry-Perot filter can be manufactured. And meanwhile, the silicon dioxide insulating layer of the SOI wafer can also be used as an etching stopping layer, so that the condition of excessive etching is avoided, and the manufacturing yield of the filter is further improved. When the bonding layer and the silicon dioxide insulating layer of the SOI wafer are etched, an etching method combining advanced oxide etching and reactive ion etching is adopted, isotropy and anisotropy are integrated, and the limitation of a single process is overcome. A certain dislocation amount of linear offset is reserved during patterning of bonding metal, gold-tin eutectic bonding is adopted, the problem of leading-out of top and bottom electrodes is solved, and the machining cost and uncertainty are reduced.

The invention discloses a gallium oxide-based Schottky barrier diode and a preparation method thereof. The method comprises the following steps: preparing a gallium oxide substrate; performing oxygen plasma treatment in a reactive ion etching system; feeding the sample into a tubular furnace, and annealing in an air atmosphere; then sending the annealed sample into electron beam evaporation equipment for back metal silver electrode growth; next, the sample is sent into rapid thermal annealing equipment to be annealed in the N2 atmosphere, and ohmic contact is formed; then, under the conditions that the growth speed is 0.01-0.1 nm / s and the vacuum degree is lower than 1 * 10 <-4 > Pa, field plate oxide Al2O3 grows on the surface treatment acting layer of the substrate through electron beam evaporation; and finally growing a metal anode at the top of the device by electron beam evaporation equipment. According to the technical scheme provided by the invention, the problem of preparing the gallium oxide-based Schottky barrier diode with low forward conduction loss under the condition of maintaining high breakdown voltage of the device is solved.

The invention provides an infrared detector deep mesa etching process based on three layers of masks and an infrared detector, and belongs to the field of infrared detector mesa etching. The process comprises the following steps: spin-coating a stress buffer layer on the surface of a superlattice epitaxial layer, and curing and forming; depositing a hard mask serving as an etching barrier layer; depositing an inorganic oxide; spin-coating photoresist to form a composite patterned top layer, and then forming a mesa pattern through a photoetching process; taking the mesa pattern as a mask, and transferring the mesa pattern to the hard mask through reactive ion etching; etching the stress buffer layer by adopting plasma until the surface of the superlattice epitaxial layer is exposed; the three layers of masks are used as blocking, deep etching is carried out through inductively coupled plasma, and the etching depth is 5.6-6 microns; a post-processing step; according to the process provided by the invention, high-quality and high-aspect-ratio mesa etching can be realized on the premise of not introducing extra pollution and remarkably increasing the cost, and the process is suitable for preparing a deep-mesa and high-aspect-ratio device.

The invention discloses a preparation method of a superconducting nanowire single-photon detector capable of keeping high detection efficiency in a liquid helium temperature region. The preparation method comprises the following steps: adopting a double-layer substrate formed by silicon oxide and silicon; the method comprises the following steps: growing a niobium nitride film on a silicon oxide surface of a substrate through radio frequency magnetron sputtering to serve as a buffer layer, growing a niobium nitride film through direct current magnetron sputtering, and accurately measuring and controlling the thickness through XRR; the method comprises the following steps: preparing a double-line parallel nanowire structure in a manner of exposing PMMA A4 electron beam glue by electron beams, and transferring a nanowire pattern to a niobium nitride film in a reactive ion etching manner; the method comprises the following steps of: removing photoresist above a region needing to be etched on a silicon oxide surface of a substrate in a manner of exposing the AZ4620 photoresist through ultraviolet laser direct writing, and then etching silicon oxide and silicon from the silicon oxide surface of a device through reactive ion etching to prepare a suspension bridge structure. The high detection efficiency of the device is ensured while the working temperature of the device is greatly improved.

A method for etching a substrate includes pulsing an RF power at a given frequency to generate a plasma for etching the substrate where each pulse period has an ON-state and an OFF-state comprising a duty cycle, selecting an ON-state duration of the duty cycle based on, at least in part, a first duration for restriking the plasma, a second duration for a minimum on-time per a given RF power source providing the RF power, and a third duration for the plasma to reach a steady state, selecting an OFF- state duration of the duty cycle for each pulse period to alter a profile loading, a iso-dense depth loading, or a critical dimension (CD) loading etching effect associated with a feature to be formed on the substrate, and forming the feature by using the duty cycle for the RF power to etch the substrate.

The invention belongs to the technical field of electronic packaging and printed circuit boards, and particularly relates to a method for improving the bending resistance of a flexible circuit board, which comprises the following steps: after plasma pretreatment is carried out on the surface of a polyimide substrate, a three-dimensional nano-column array structure is constructed by depositing gold nanoparticles as a mask and combining reactive ion etching; then removing the mask to obtain a clean polyimide nano structure; and depositing a titanium / copper seed crystal layer through magnetron sputtering, and realizing conformal filling and coating of the copper conductive layer on the nano structure by adopting pulse reverse electroplating to form an adhesive-free mechanical interlocking interface. An adhesive-free three-dimensional mechanical interlocking structure is used for replacing an adhesive layer which is weak in physical performance and prone to fatigue failure, and the structural weak link that a traditional flexible circuit board is layered and cracked first under dynamic bending stress is thoroughly removed.

The utility model discloses waste gas treatment equipment for a reactive ion etching machine and belongs to the field of etching machines. An air inlet and an air outlet are formed in the side surface of the shell; an induced draft fan is arranged on the air inlet; the interior of the shell is fixedly connected with an isolation box; a through hole communicated with the isolation box is formed in the side surface of the shell; the top end of the side face of the isolation box is fixedly connected with a partition plate I. The other end of the partition plate I is fixedly connected to the inner wall of the shell. An air inlet is formed in the center of the top end of the isolation box, an air outlet I is formed in the center of the bottom end of the isolation box, and air outlets II are formed in the two sides of the air outlet; the partition plate II is provided with a through hole I. The top end of the side face of the isolation box is provided with a through hole II. The air outlet I is communicated with the through hole I through a pipe; a plurality of rows of sealing plates perpendicular to the penetrating holes are fixedly connected into the isolation box. And a pumping box is arranged in the isolation box. According to the utility model, not only is the filter material convenient to replace, but also the waste gas can be filtered twice when being purified, so that the purified waste gas is ensured to meet the standard.

This invention relates to a GaN-based pn junction diode device with a polarized beveled termination structure and its fabrication method. The device includes a cathode, a GaN substrate, an epitaxial layer, and an anode. The epitaxial layer comprises a lightly doped n-type GaN layer, an intrinsic GaN layer, and a p-type doped GaN layer grown in a single epitaxial growth process. The anode ohmic contact metal is placed on the p-type doped GaN layer, and the cathode ohmic contact metal is placed on the back side of the GaN substrate. It also includes a polarized beveled termination structure formed at the interface containing the pn junction, using inductively coupled plasma reactive ion etching (ICP-R) and a photoresist mask. The photoresist mask is formed using thick photoresist, followed by high-temperature heating and annealing to form the reflow morphology of the photoresist. Finally, wet repair and a passivation layer are applied to suppress the beveled n-type donor surface states of the polarized beveled termination structure. This invention effectively alleviates the boundary electric field concentration problem of GaN-based pn junctions and improves the breakdown voltage of GaN-based pn junctions.

A method tests the stress robustness of a semiconductor substrate. The method includes: forming a nitride layer on a surface of the semiconductor substrate, the nitride layer being directly deposited on the surface of the semiconductor substrate or on a native oxide layer that is interposed on the surface; cooling the semiconductor substrate and the nitride layer; patterning the nitride layer into a patterned nitride by photolithography including a step of reactive ion etching with ions produced from a gas, which includes hydrogen or a hydrogen compound or both; processing the patterned nitride and the semiconductor substrate at a temperature of not less than 800° C. and not more than 1300° C. in a nitrogen atmosphere to induce the formation of dislocations at an interface between the patterned nitride and the semiconductor substrate; and evaluating at least one property that is related to the formed dislocations.

The application provides an infrared detector deep mesa etching process based on a three-layer mask and an infrared detector, and belongs to the field of infrared detector mesa etching. The process comprises the following steps: spin-coating a stress buffer layer on the surface of a superlattice epitaxial layer and curing the stress buffer layer; depositing a hard mask as an etching barrier layer; depositing an inorganic oxide; spin-coating a photoresist to form a composite patterned top layer, and then forming a mesa pattern through a photolithography process; taking the mesa pattern as a mask, transferring the mesa pattern to the hard mask through reactive ion etching; etching the stress buffer layer by using plasma until the surface of the superlattice epitaxial layer is exposed; taking the three-layer mask as a barrier, performing deep etching by using inductively coupled plasma, and the etching depth is 5.6-6 microns; and performing a post-processing step. The process of the application can realize high-quality and high-aspect-ratio mesa etching without introducing additional pollution and significant cost increase, and is suitable for the preparation of deep mesa and high-aspect-ratio devices.

The present invention discloses an etching method for an MRAM magnetic tunnel junction, comprising: Step 1, a main etching step with an etching amount of t1 is carried out by using ion beam etching and / or reactive ion etching: the direction angle of the ion beam is 10° to 60°, and the bias voltage of the reactive ion etching is 400 - 1000 V; Step 2, a cleaning step with an etching amount of t2: the bias voltage of the reactive ion etching used is 50 V - 400 V, and the pulse duty ratio is 5% - 50%. t1:t2 ≥ 0.5. After the cleaning step is completed, the etching morphology on the bottom electrode or the bottom dielectric layer is a square groove; Step 3, in-situ protection: a film is deposited for in-situ protection. The present invention combines RIE and IBE etching. Through the arrangement of the etching sequence and the selection of the etching parameters, while significantly improving the etching effect of small-size dense magnetic tunnel junctions, it is also applicable to the etching of non-dense magnetic tunnel junctions. Thus, the problems of low selectivity and low steepness during the etching of dense patterns are solved. Further, the square etching groove can greatly improve the TMR and service life of the MTJ junction and eliminate bottom deposition.

The invention discloses a preparation method of an efficient graphene-carbon nanotube transistor sensor and a method for detecting Hg < 2 + > by using the sensor, and the preparation method of the efficient graphene-carbon nanotube transistor sensor comprises the following steps: S1, preparing graphene; s2, transferring the graphene; s3, carrying out reactive ion etching and thermal evaporation on the gold electrode; s4, surface functional modification of the sensor; the high-quality graphene film is prepared by a chemical vapor deposition method, and is transferred to the surface of the silicon wafer on which the carbon nanotubes are pre-grown by a PMMA (polymethyl methacrylate) auxiliary transfer method to form a unique bent and curled structure, and the structure not only greatly increases the effective specific surface area of the material, but also gives full play to the synergistic effect of the graphene and the carbon nanotubes, so that the performance of the material is improved. The electrochemical activity of the sensor is obviously improved, so that the Hg < 2 + > detection sensitivity reaches a picomole level.

The invention discloses a method for preparing a thermoelectric device based on a monatomic layer IV-VI group nanobelt. The method comprises the following steps: synthesizing a monatomic layer IV-VI group nanosheet through a one-pot method solution, transferring the monatomic layer IV-VI group nanosheet to a SiO2 / Si substrate, patterning the monatomic layer IV-VI group nanosheet into a nanobelt through electron beam lithography and reactive ion etching technologies, and then depositing a metal contact point and assembling the metal contact point into the thermoelectric device. Based on the excellent thermoelectric performance of the monatomic layer nanobelt predicted through theoretical research, the thermoelectric figure of merit (ZT) is remarkably improved through the quantum confinement effect and the low heat conductivity characteristic of the monatomic layer nanobelt, and the method is suitable for the fields of waste heat power generation, electronic cooling and the like. The technological process is controllable, and potential large-scale production capacity is achieved. According to the method, the thermoelectric performance is optimized by accurately controlling the thickness of the nanosheets and the width of the nanoribbons, the experimental steps are closely combined with theoretical prediction, the method is suitable for various IV-VI family materials, and a new technical path is provided for development of efficient thermoelectric devices.

The application discloses a method for improving the moisture and heat resistance reliability of a bump connection structure, which comprises the following steps: (1) performing hydroxylation treatment on the bump connection structure for semiconductor device connection; (2) performing treatment on the bump connection structure with an organic compound to form a self-assembled molecular film; (3) performing dehydration treatment on the bump connection structure; and (4) performing etching on the self-assembled molecular film by using a reactive ion etching technology. Finally, the self-assembled molecular film with regular orientation and close arrangement is formed on the surface of the bump connection structure, especially at the undercut structure. The preparation method is simple, the self-assembled molecular film formed has high stability and corrosion resistance, and the reliability and stability of the bump in a moisture and heat environment can be effectively improved.

A method of dicing a semiconductor wafer comprises steps of a) positioning a stencil mask over the semiconductor wafer, with the stencil mask being spaced from the semiconductor wafer by a gap such that the stencil mask does not touch a component arranged on the semiconductor wafer, the stencil mask having an aperture; and b) subsequently etching through the semiconductor wafer by performing a reactive ion etch, wherein the stencil mask controls the etch. The method may allow a wafer to be diced without the use of die attach tape and without need for a cleaning step, and may be useful for dicing wafers bearing microelectromechanical systems. Also provided are a stencil mask and system useful in the method.

The invention belongs to the field of micro-nano structures, and relates to a double-layer gold nanopore structure supported by a nano needle tip as well as a preparation method and application of the double-layer gold nanopore structure. According to the preparation method, the double-layer gold nanopore structure supported by the nano needle tip is obtained through an electron beam thermal evaporation system, a polystyrene microsphere self-assembly technology and reactive ion etching (RIE), the preparation process is simple, the cost is low, the repeatability is good, the structural stability is good, and the tolerance is high. Compared with a single-layer gold nanopore structure, the single-layer gold nanopore structure not only has more modes, but also presents complex multi-mode response dependent on pumping wavelength.

The invention relates to a method for determining crystal defects in a workpiece made of monocrystalline silicon, comprising the following steps: (i) reactive ion etching at least one surface of the workpiece in a gas mixture comprising oxygen and one or more halogen-containing compounds selected from the group consisting of elemental halogen X2, hydrogen halide HX and nitrogen halide NHnX3-n, wherein X is selected from the group of Cl and Br, and 0 ≤ n ≤ 2, the flow rate of oxygen and of each of the one or more halogen-containing compounds is not less than 5 sccm and not more than 100 sccm, and the at least one surface of the workpiece to be etched is exposed to the gas mixture for no less than 10 seconds and no more than 20 minutes; and (ii) identifying defects on the etched surface of the workpiece by means of light scattering measurement.

The present invention discloses an amorphous tungsten superconducting nanowire single-photon detector (SNSPD), comprising a photosensitive component, which is an amorphous tungsten superconducting nanowire. The amorphous tungsten superconducting nanowire is prepared by the following steps: (1) growing an amorphous tungsten thin film on a substrate; and (2) etching the amorphous tungsten film into a circuitous nanowire structure using electron beam exposure and reactive ion etching to obtain the amorphous tungsten superconducting nanowire. The present invention uses tungsten nanowires with good stability as the main material of the SNSPD, thereby improving the robustness of the SNSPD preparation process and extending the service life of the SNSPD device in practical applications.

This invention discloses a method for fabricating a gallium oxide photodetector based on reactive ion etching to enhance the synaptic effect, comprising the following specific steps: Step 1: Growing a gallium oxide layer on a substrate; Step 2: Patterning the gallium oxide layer using photolithography; Step 3: Etching the gallium oxide layer; Step 4: Forming a gallium oxide substrate on the etched gallium oxide layer using photolithography, and depositing a stacked metal on the surface of the gallium oxide layer; after peeling the gallium oxide layer and the stacked metal from the substrate, an electrode is obtained; Step 5: Annealing the electrode to alloy it and form an ohmic contact. This invention uses reactive ion etching to etch the gallium oxide layer, inducing the formation of more oxygen vacancies within the gallium oxide layer, thereby effectively enhancing the synaptic properties of the gallium oxide photodetector in biomimetic applications; it can better meet the needs of large-scale industrial applications while reducing manufacturing costs and process difficulty.

The application relates to a two-dimensional material heterojunction device and a preparation method thereof, and belongs to the field of two-dimensional materials. The preparation method processes an embedding electrode after etching a substrate by a reactive ion etching machine, guarantees that the electrode is basically consistent with the substrate in height, effectively improves surface flatness, is favorable for avoiding rupture of a heterojunction structure when a multilayer heterojunction structure is prepared, is favorable for forming a heterojunction structure with more layers, and greatly improves the success rate and device quality of the multilayer heterojunction device. The preparation method also controls a fitting speed in a dry transfer process by thermal expansion and cold contraction to reduce damage to materials in the fitting process, and greatly improves the success rate and device quality of the multilayer heterojunction device.

The present disclosure provides an article including a multilayer optical film including first optical layers and second optical layers, plus a boundary layer directly attached to a major surface of the multilayer optical film. The boundary layer includes a major surface opposite the multilayer optical film that has a nanostructured anisotropic surface. A method of making the article is also provided, including attaching a boundary layer directly to a major surface of a multilayer optical film, depositing an etch mask material on a major surface of the boundary layer opposite the multilayer optical film, and subsequently or concurrently reactive ion etching to anisotropically remove material in unmasked areas.

The invention discloses reactive ion etching equipment and an etching method for processing a semiconductor device, and relates to the technical field of semiconductor etching, and the reactive ion etching equipment comprises a reaction cavity which is provided with an upper gas distribution area and a lower sample placement area; wherein at least a first chamber and a second chamber are formed in the reaction chamber, the first chamber and the second chamber cover part of the wafer, and airflow control units are arranged in the first chamber and the second chamber; etching gas passes through the plasma from top to bottom and forms a sheath layer above the sample stage, so that ions generated by the plasma pass through the sheath layer and then are incident towards the surface of the wafer. Through the combination of structural partition, movable recovery and variable gas supply, sample table cooperation and closed-loop sequential control, the etching stability in a continuous mode is kept, the influence of by-product accumulation on the etching precision in a pulse mode is reduced, and the repeatability, the selective control capability and the device yield of pulse etching are improved.

A semiconductor wafer of single-crystal silicon has an oxygen concentration per new ASTM of not less than 5.0×1017 atoms / cm3 and not more than 6.5×1017 atoms / cm3; a nitrogen concentration per new ASTM of not less than 1.0×1013 atoms / cm3 and not more than 1.0×1014 atoms / cm3; a front side having a silicon epitaxial layer wherein the semiconductor wafer has BMDs whose mean size is not more than 10 nm determined by transmission electron microscopy and whose mean density adjacent to the epitaxial layer is not less than 1.0×1011 cm−3, determined by reactive ion etching after having subjected the wafer covered with the epitaxial layer to a heat treatment at a temperature of 780° C. for a period of 3 h and to a heat treatment at a temperature of 600° C. for a period of 10 h.

The invention relates to a preparation method of a supporting table structure for reducing deformation stress of a linear array detector, solves the problems of height difference, difficulty in inverted interconnection process and large internal stress of a common electrode groove of an existing II-type superlattice linear array detector, and belongs to the technical field of infrared detectors. The preparation method comprises the following steps: (1) cleaning an epitaxial wafer; (2) depositing a SiO2 hard mask in a PECVD (plasma enhanced chemical vapor deposition) mode; (3) photoetching; (4) etching the SiO2 hard mask by adopting an RIE (Reactive Ion Etching) process; (5) degumming and cleaning; (6) etching by using an ICP (inductively coupled plasma) dry method; (7) corroding, cleaning and blow-drying the etched epitaxial wafer; (8) etching residual SiO2 by using RIE (Reactive Ion Etching); (9) carrying out pixel etching and passivation trepanning; and (10) electrode deposition. According to the design, the internal stress of the infrared column detector chip is reduced, the stress of pixels near the common electrode grooves is more uniform, and the photoelectric response uniformity of the detector is improved.

The invention relates to a method for regulating and controlling the retentivity of a ferroelectric domain wall memory through the size of a device, which comprises the following steps of: epitaxially growing a BiFeO3 film with the thickness of 200nm on a SrTiO3 (001) substrate which is beveled by 2 degrees, ensuring the quality of the film by adopting pulsed laser deposition, and forming a Pt planar electrode structure on the surface of the film through magnetron sputtering, electron beam photoetching and reactive ion etching, the polarization overturning area is controlled by adjusting the electrode gap, the retentivity is tested by combining an I-V curve and a PFM spectrum, and the result shows that when the overturning area is larger than 7 * 10 < 6 > nm < 2 >, the device can keep the polarization state for a long time, and when the area is reduced to 1.3 * 10 < 4 > nm < 2 >, the retentivity disappears. According to the invention, the retention rule of size dependence is defined, the influence of a depolarization field and ferroelastic energy is effectively overcome, and the reliability and information retention time of the memory are remarkably improved.