CN102633229B - Method for preparing superlens with planar imaging surface by using twice ion beam etching technology - Google Patents

Abstract

The invention provides a method for preparing a superlens with a plane imaging surface by utilizing a twice ion beam etching technology, which mainly comprises the following steps: and etching the semi-cylindrical groove by using the IBE to obtain a circular arc curved surface groove which has the same curvature radius but reduced diameter depth, then depositing a multilayer film in the circular arc curved surface groove, and etching the multilayer film by using the IBE to obtain the super lens with a plane imaging surface. According to the method, a thin film with non-uniform thickness is not required to be prepared to realize the manufacture of the planar super lens, the circular arc curved surface groove with any diameter and depth and the same curvature as the semi-cylindrical groove can be obtained only by adopting a common IBE technology, and the super lens with the planar imaging surface can be prepared on the circular arc curved surface groove by adopting the IBE etching technology again after a multilayer film with uniform thickness is deposited on the circular arc curved surface groove. The invention can obtain the arc curved surface groove with any diameter and depth, which has the same curvature as the semi-cylindrical groove, only by adopting the conventional ion beam etching technology, the film deposition technology and the reactive ion etching technology, and prepare the super lens with the imaging surface as a plane on the basis.

Description

A method for preparing a superlens with a flat imaging surface using two ion beam etching techniques

technical field

The invention relates to the technical field of super-lens preparation, in particular to a method for preparing a super-lens whose imaging surface is a plane by using two ion beam etching techniques.

Background technique

It is well known that conventional lithographic resolution is limited by the diffraction limit. For this reason, research on super-resolution lithographic imaging that breaks through the diffraction limit is particularly important. Metalenses deposit periodic metal and dielectric film layers in semi-cylindrical grooves to form an artificial material suitable for evanescent wave transmission, thereby achieving reduced or enlarged super-resolution lithographic imaging. The application of metalens used to realize zoom-out super-resolution imaging is greatly limited because the imaging surface is a curved surface, so the preparation of a metalens with a flat imaging surface can be used for nanolithography imaging, sensing, plasma manipulation, etc. aspect. In addition, the cost of producing mask patterns with a line width of less than 100 nanometers is relatively high by processing technologies such as focused particle beams. The size of mask patterns can be expanded to at least 2 times, which will reduce the production cost of the mask very well.

A method of manufacturing a metalens with a flat imaging surface is to use the principle of grayscale exposure to process slits on the mask through which the deposited particles can pass; to move the mask slits during the film deposition process so that the deposition area is in the Move on the substrate; by controlling the deposition time of each region of the substrate to control the thickness of the film deposited in each region, thereby modulating the thickness distribution of the film layer, and realizing the preparation of a superlens with a flat imaging surface. This method is difficult to control because the modulation range of the thickness of each layer is on the order of ten nanometers. At the same time, this method involves large-scale transformation of existing coating equipment, which is time-consuming and expensive, and the operability is not strong.

This method only needs to adopt conventional ion beam etching technology, thin film deposition technology, and reactive ion etching technology to obtain arc-shaped grooves with any diameter and depth that are the same as the curvature of semi-cylindrical grooves, and on this basis The metalens whose imaging surface is flat is prepared, the operability is greatly improved, and the cost is low.

Contents of the invention

The technical problem to be solved by the present invention is: to solve the problem that the imaging surface of the existing super-lens used for reducing super-resolution imaging is a curved surface, a method for preparing a super-lens with a flat imaging surface by using two ion beam etching techniques is proposed. This method only needs to use conventional ion beam etching technology, thin film deposition technology, and reactive ion etching technology to obtain arc-shaped grooves with any diameter and depth that are the same as the curvature of semi-cylindrical grooves, and on this basis A metalens with a flat imaging surface is prepared.

The technical solution adopted by the present invention to solve its technical problems is: a method for preparing a hyperlens whose imaging surface is plane by using two ion beam etching (IBE) techniques, the steps are as follows:

Step (1) Coating an organic film layer in the prepared semi-cylindrical groove. The coating thickness of the organic film layer is 4.6-4.8 μm, and the diameter width of the semi-cylindrical groove is 800nm-1 μm;

Step (2) Etching the 4.6-4.8 μm organic film layer to a thickness of 100-200 nm by reactive ion etching (RIE).

Step (3) Utilizes the characteristics that the IBE etching speeds of various materials are not much different under appropriate conditions, and by controlling the etching time, after removing the remaining organic film layer, a film with a diameter depth of 150-200nm and a radius of curvature of 500nm can be obtained. Arc-shaped surface groove;

Step (4) depositing a multilayer film with a thickness of 250-300 nm in the structure obtained in the step (3);

Step (5) Coating an organic film layer on the surface of the structure obtained in the step (4). The coating thickness of the organic film layer is 600-700nm;

Step (6) utilizes again the characteristic that the IBE etching speeds of various materials are not much different under appropriate conditions, and obtains a superlens with a flat imaging surface by controlling the etching time.

The organic film layer coated in the step (1) and the step (5) can be photoresist, electron beam glue or Spin of glass (SOG) etc., the semi-cylindrical groove in the step (1) The material of the groove is quartz or organic transparent material, and the organic film layer plays the role of filling the groove in the step (1) and the step (5) and playing the role of masking in the subsequent IBE etching process.

In the step (2), the etching power of RIE is 90-110W, the etching gas is oxygen, the etching flow rate is 40-60 sccm, and the etching time is 9-12 minutes.

In the step (3) and the step (6), the substrate cooling temperature during IBE etching is 10-15°C, the etching ion beam current is 60-100A, the electron beam current is 80-120mA, and the Ar The gas flow is 3-4 sccm, the etching time in the step (3) is 15-20 minutes, and the reagent for removing the remaining organic film layer in the arc-shaped groove is acetone, ethanol and the like. The etching time in the step (6) is 27-35 minutes. In order to avoid the influence of temperature on the material of the semi-cylindrical groove and the etching rate of the coated organic film layer during etching, it is necessary to stop etching for 2-4 minutes after etching for 3-5 minutes before proceeding to the next step of etching.

In the step (4), the film deposition method can be magnetron sputtering, vacuum evaporation or atomic layer deposition, etc., and the material of the deposited multilayer film can be silver, silicon dioxide, aluminum oxide, etc. The multilayer film is periodically alternating film layers, and the thickness of each layer is 15-20nm.

Compared with existing methods, the advantages of the present invention are:

(1) It can be known from the steps (2) and (3) that the present invention only needs to adopt conventional reactive ion etching technology and ion beam etching technology to obtain a circle with the same arbitrary diameter and depth as the semicylindrical groove curvature. Curved grooves. The same curvature ensures that the scaling ratio of the hyperlens with the imaging surface as a plane and the hyperlens with the imaging surface as a curved surface are the same; at the same time, the diameter depth of the semi-cylindrical groove is reduced, which effectively reduces the deposition rate of the inner and outer layers of the groove. The gap makes the deposition thickness of the film layer more uniform, and at the same time reduces the problem of film layer fracture caused by stress; in addition, the smaller diameter and depth of the semi-cylindrical groove makes the thickness of the deposited multilayer film larger than that of the arc-shaped surface The diameter depth of the groove makes it possible to fabricate a metalens whose imaging surface is a plane. Compared with chemical polishing processing technology (CMP), this method achieves controllable nanometer-scale polishing thinning, and ensures the curvature and surface shape of the semi-cylindrical groove; Compared with the method, the sedimentation of particles in the groove is reduced, and the cleanliness of the groove is improved.

(2) From the above steps (5) and (6), it can be known that the present invention can prepare a superlens with a flat imaging surface through arc-shaped curved surface grooves. Compared with the method of preparing a planar metalens by depositing alternating layers of non-uniform thickness, the method has stronger operability and simple process. Compared with the metalens whose imaging surface is a curved surface, it has a wider application range and prospect.

Description of drawings

Fig. 1 is the flowchart of the inventive method;

Fig. 2 is in the embodiment 1 of the present invention, the sectional structure schematic diagram of coating photoresist in semi-cylindrical groove and filling up semi-cylindrical groove;

3 is a schematic diagram of a cross-sectional structure of photoresist thinned by conventional reactive ion etching (RIE) in Example 1 of the present invention;

Fig. 4 is in the embodiment 1 of the present invention, adopts ion beam etching (IBE) photoresist and quartz to obtain thinned arc-shaped curved surface groove, the section after removing remaining photoresist in the arc-shaped curved surface groove Schematic;

5 is a schematic cross-sectional structure diagram of a multi-layer film deposited by vacuum evaporation in an arc-shaped curved surface groove in Example 1 of the present invention;

6 is a schematic diagram of a cross-sectional structure of photoresist coated on the structure shown in FIG. 5 in Embodiment 1 of the present invention;

Fig. 7 is in embodiment 1 of the present invention, adopts ion beam etching (IBE) photoresist and multi-layer film to obtain the sectional structure schematic diagram of the hyperlens whose imaging plane is plane;

In the figure: 1 represents the substrate material quartz; 2 represents various types of photoresist; 3 represents the silver film material; 4 represents the silicon dioxide film material.

Detailed ways

The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments. But the following examples are only limited to explain the present invention, and the protection scope of the present invention should include the whole content of claim, and promptly can realize the whole content of claim of the present invention to those skilled in the art through following embodiment.

Embodiment 1, on the arc-shaped groove that diameter depth is 150nm, prepare the hyperlens that imaging surface is plane, and manufacturing process is as follows:

(1) On a semi-cylindrical trench prepared on a 1mm thick quartz substrate, AR-P3100 photoresist was coated by spin coating. In order to fill up the semi-cylindrical grooves, a method of coating multiple times at a spin coating speed of 2000rpm/15sec was used. After multiple coatings, when the coating thickness of AR-P3100 reaches 4.6 microns, the semi-cylindrical groove is filled, as shown in Figure 2, 1 represents the substrate material quartz; 2 represents various types of photolithography glue.

(2) Thinning the AR-P3100 photoresist by RIE etching, the etching power is 100W, the gas used for etching is oxygen, the flow rate is 50 sccm, and the etching time is 10 minutes and 30 seconds, as shown in Figure 3, 1 represents the substrate material quartz; 2 represents various types of photoresists.

(3) The conformal thinning of semi-cylindrical grooves is realized by using the characteristic that the etching rate of AR-P3100 photoresist and quartz is close to the same by IBE under appropriate conditions. The etching gas is Ar gas, the flow rate is 3.6sccm, the etching ion beam current is 80A, the electron beam current is 100mA, the etching substrate cooling temperature is 15°C, and the etching time is 18 minutes (excluding the time to stop etching) . In order to avoid the influence of temperature changes on the material of the semi-cylindrical groove and the etching rate of the coated organic film layer during etching, it is necessary to stop etching for 2 to 4 minutes after etching for 3 to 5 minutes before proceeding to the next step of etching . After removing the remaining AR-P3100 photoresist, an arc-shaped groove with a diameter and depth of 150nm is finally obtained, and its radius of curvature is consistent with the original semi-cylindrical groove. As shown in Figure 4, 1 represents the substrate material quartz .

(4) Prepare alternate multilayer films of silver and silicon dioxide by vacuum evaporation in the arc-shaped curved surface groove, the thickness of each layer of film is 10-15nm, and the total thickness of the multilayer film is 250nm. As shown in Figure 5, 1 represents the substrate material quartz; 3 represents the silver film material; 4 represents the silicon dioxide film material.

(5) Coating AR-P3120 photoresist on the structure shown in FIG. 5 by spin coating, the coating speed is 4000 rpm, the coating time is 30 seconds, and the coating thickness is 600 nm. As shown in Figure 6, 1 represents the substrate material quartz; 2 represents various types of photoresist; 3 represents the silver film material; 4 represents the silicon dioxide film material.

(6) Using IBE to etch the multilayer film composed of AR-P3120 photoresist, silver and silicon dioxide. The etching gas uses Ar gas, the flow rate is 3.26sccm, the etching ion beam current is 80A, the electron beam current is 100mA, the etching substrate cooling temperature is 10°C, and the etching time is 27 minutes (not including the time to stop etching) . In order to avoid the influence of temperature on the material of the semi-cylindrical trench and the etching rate of the coated organic film layer during etching, it is necessary to stop etching for 2 to 4 minutes after etching for 3 to 5 minutes before proceeding to the next step of etching. As shown in Figure 7, 1 represents the substrate material quartz; 3 represents the silver film material; 4 represents the silicon dioxide film material.

Embodiment 2, on the circular arc-shaped groove that diameter depth is 200nm, prepare the hyperlens that imaging plane is plane, and manufacturing process is as follows:

(1) On a semi-cylindrical trench prepared on a 1mm thick quartz substrate, AR-P3100 photoresist was coated by spin coating. In order to fill up the semi-cylindrical grooves, a method of coating multiple times at a spin coating speed of 2000rpm/15sec was used. After multiple coatings, when the coating thickness of AR-P3100 reaches 4.8 microns, the semi-cylindrical groove is filled, as shown in Figure 2, 1 represents the substrate material quartz; 2 represents various types of photolithography glue.

(2) Thinning the AR-P3100 photoresist by RIE etching, the etching power is 100W, the gas used for etching is oxygen, the flow rate is 50 sccm, and the etching time is 11 minutes and 30 seconds, as shown in Figure 3, 1 represents the substrate material quartz; 2 represents various types of photoresists.

(3) The conformal thinning of semi-cylindrical grooves is realized by using the characteristic that the etching rate of AR-P3100 photoresist and quartz is close to the same by IBE under appropriate conditions. The etching gas is Ar gas, the flow rate is 3.6sccm, the etching ion beam current is 80A, the electron beam current is 100mA, the etching substrate cooling temperature is 15°C, and the etching time is 16 minutes and 30 seconds (not including the time to stop etching). time). In order to avoid the influence of temperature changes on the material of the semi-cylindrical groove and the etching rate of the coated organic film layer during etching, it is necessary to stop etching for 2 to 4 minutes after etching for 3 to 5 minutes before proceeding to the next step of etching . After removing the remaining AR-P3100 photoresist, an arc-shaped groove with a diameter and depth of 200nm is finally obtained, and its radius of curvature is consistent with the original semi-cylindrical groove. As shown in Figure 4, 1 represents the substrate material quartz .

(4) Prepare alternate multilayer films of silver and silicon dioxide by vacuum evaporation in the arc-shaped grooves, the thickness of each layer is 10-15nm, and the total thickness of the multilayer film is 300nm. As shown in Figure 5, 1 represents the substrate material quartz; 3 represents the silver film material; 4 represents the silicon dioxide film material.

(5) Coating AR-P3120 photoresist on the structure shown in FIG. 5 by spin coating, the coating speed is 3000 rpm, the coating time is 20 seconds, and the coating thickness is 700 nm. As shown in Figure 6, 1 represents the substrate material quartz; 2 represents various types of photoresist; 3 represents the silver film material; 4 represents the silicon dioxide film material.

(6) Utilize IBE to etch the multilayer film composed of AR-P3120 photoresist, silver and silicon dioxide. The etching gas is Ar gas, the flow rate is 3.26sccm, the etching ion beam current is 80A, the electron beam current is 100mA, the etching substrate cooling temperature is 10°C, and the etching time is 32 minutes (excluding the time of stopping etching) . In order to avoid the influence of temperature on the material of the semi-cylindrical trench and the etching rate of the coated organic film layer during etching, it is necessary to stop etching for 2 to 4 minutes after etching for 3 to 5 minutes before proceeding to the next step of etching. As shown in Figure 7, 1 represents the substrate material quartz; 3 represents the silver film material; 4 represents the silicon dioxide film material.

The parts not described in detail in the present invention belong to the well-known technology in the art.

Claims (5)

1. a method for preparing a superlens that utilizes two ion beam etching techniques to prepare an imaging surface is a plane, and is characterized in that: the concrete steps of the method are as follows: Step (1) Coating an organic film layer in the prepared semi-cylindrical groove; the coating thickness of the organic film layer is 4.6-4.8 μm, and the diameter width of the semi-cylindrical groove is 800 nm-1 μm; Step (2) using reactive ion etching (RIE) to etch the 4.6-4.8 μm organic film layer to a thickness of 100-200 nm; Step (3) Utilizes the characteristics that the IBE etching speeds of various materials are not much different under appropriate conditions, and by controlling the etching time, after removing the remaining organic film layer, a film with a diameter depth of 150-200nm and a radius of curvature of 500nm can be obtained. Arc-shaped surface groove; Step (4) depositing a multilayer film with a thickness of 250-300 nm in the structure obtained in the step (3); Step (5) coating the organic film layer on the surface of the structure obtained in the step (4); the coating thickness of the organic film layer is 600-700nm; Step (6) utilizes again the characteristic that the IBE etching speeds of various materials are not much different under appropriate conditions, and obtains a superlens with a flat imaging surface by controlling the etching time. 2. utilize twice ion beam etching technique according to claim 1 to prepare the hyperlens preparation method that imaging surface is plane, it is characterized in that: the organic lens coated in the described step (1) and the described step (5) The film layer is a photoresist, and the material of the semicylindrical groove in the step (1) is quartz or organic transparent material, and the organic film layer plays a filling role in the step (1) and the step (5). The flat trench and the role of masking in the subsequent IBE etching process. 3. utilize twice ion beam etching technique according to claim 1 to prepare the hyperlens preparation method that imaging plane is plane, it is characterized in that: in described step (2), the etching of reactive ion etching (RIE) The power is 90-110W, the etching gas is oxygen, the etching flow rate is 40-60 sccm, and the etching time is 9-12 minutes. 4. Utilize twice ion beam etching technology according to claim 1 to prepare the hyperlens preparation method that imaging plane is plane, it is characterized in that: in described step (3) and described step (6), IBE etching When the substrate cooling temperature is 10-15°C, the etching ion beam current is 60-100A, the electron beam current is 80-120mA, and the Ar gas flow rate is 3-4 sccm, the etching time in the step (3) is 15～20 minutes, the reagent that removes remaining organic film layer in the arc-shaped groove is acetone or ethanol; In the described step (6), the etching time is 27～35 minutes; During etching, in order to avoid temperature from affecting the semi-cylindrical groove Influenced by the material of the groove and the etching rate of the coated organic film layer, it is necessary to stop etching for 2-4 minutes after etching for 3-5 minutes before proceeding to the next step of etching. 5. utilize twice ion beam etching technology according to claim 1 to prepare the hyperlens preparation method that imaging plane is plane, it is characterized in that: in described step (4), the mode of film deposition is magnetron sputtering , Vacuum evaporation or atomic layer deposition, the material of the deposited multilayer film is silver, silicon dioxide or aluminum oxide; the multilayer film is periodically alternating film layers, and the thickness of each layer is 15-20nm.