CN102320752B - Patterning method for material - Google Patents

Abstract

The invention discloses a material patterning method. The method comprises the following steps: 1) preparing a layer of polymer film on the substrate; 2) coating the good solvent of the polymer film on the surface of the obtained polymer film by inkjet printing to obtain a patterned high polymer film. Molecular film; 3) After preparing a layer of target material film and a layer of polystyrene film sequentially on the obtained patterned polymer film and the exposed surface of the substrate, peel off the polystyrene film after soaking in water. Vinyl film and films of all target materials except patterns and the polymer film to complete the patterning of the materials. The minimum channel length of the graphene electrode can reach 2 microns, and the graphene electrode obtained on the silicon dioxide substrate can be directly applied to an organic field effect transistor as an effective carrier injection electrode without other transfer or post-processing means.

Description

Patterning Methods of Materials

technical field

The invention relates to a method for patterning materials, in particular to a method for patterning materials by using an inkjet printing method.

Background technique

Chemically reduced graphene is considered to be an excellent conductive material because of its good mechanical properties and high electrical conductivity. It can replace the widely used indium tin oxide (ITO) in large-area, transparent, and flexible applications. In addition, because the energy level arrangement of graphene materials can match with many organic semiconductor materials, it is expected to be used as an excellent electrode injection material for many organic electronic devices. In fact, since the discovery of graphene, people have demonstrated its good technical prospects in many organic electronic devices (J.Wu, H.A.Becerril, Z.Bao, Z.Liu, Y.Chen, P.Peumans, Appl .Phys.Lett.2008, 92, 263302; G.Eda, Y.-Y.Lin, C. Mattevi, H.Yamaguchi, H.-A.Chen, I.S.Chen, C.-W.Chen, M.Chhowalla , Adv. Mater. 2010, 22, 505; J. Wu, M. Agrawal, H.c. A. Becerril, Z. Bao, Z. Liu, Y. Chen, P. Peumans, ACS Nano 2009, 4, 43). In these reported applications, the patterning of graphene is mainly achieved by photolithography and electron beam lithography.

The lift-off technique is widely used in lithography, but it has not been reported in inkjet printing. Due to the relatively large particle size of graphene, direct printing is difficult to achieve. If the graphene electrode is prepared by the lift-off process, it involves the patterning of the mask (mask) layer. How to prepare a patterned mask layer using inkjet printing technology has become a technical difficulty in the graphene exfoliation process. Once a good method is obtained, it will greatly benefit the application of this material in electronics if the cheap chemically reduced graphene material can be easily prepared by inkjet printing technology.

Contents of the invention

The purpose of the present invention is to provide a material patterning method.

The patterning method of the material provided by the invention comprises the following steps:

1) preparing a layer of polymer film on the substrate;

2) In the step 1) the surface of the obtained polymer film is coated with a good solvent for the polymer film by inkjet printing to obtain a patterned polymer film;

3) After preparing a layer of target material film and a layer of polystyrene film on the patterned polymer film obtained in step 2) and the exposed surface of the substrate, soak in water and peel off the Polystyrene film and films of all target materials except patterns and the polymer film to complete the patterning of the materials.

In the step 1), the substrate is a quartz wafer, a silicon wafer or a silicon wafer with a silicon dioxide layer on the surface, wherein, in the silicon wafer with a silicon dioxide layer, the silicon dioxide layer The thickness is 100-500 nanometers, preferably 300 nanometers; the material constituting the polymer film is polyacrylonitrile, polystyrene or polymethyl methacrylate, preferably polyacrylonitrile with a weight average molecular weight of 10000-1000000, more preferably Polyacrylonitrile with a weight average molecular weight of 200,000; the thickness of the polymer film is 1-100 nanometers, preferably 2 nanometers; the method for preparing the polymer film is a spin coating method; in the spin coating method, the rotating speed is 2000 -5000 rpm, preferably 3500 rpm;

In the method of step 2) inkjet printing, the nozzle of the inkjet printer is 20 microns to 100 microns, preferably 30 microns; the distance between adjacent droplets is 120-70 microns, preferably 87 microns; the operating temperature is 30-100 °C , preferably 80°C; the good solvent of the polymer film is selected from at least one of N,N-dimethylformamide, toluene and chlorobenzene, preferably N,N-dimethylformamide; in this step, Because the solvent used in the inkjet printing step is a good solvent for the polymer film obtained in step 1), when inkjet printing is performed, the solvent can dissolve the polymer film according to a preset pattern, exposing the surface of the substrate (such as silicon dioxide). surface, forming a patterned polymer film. In actual operation, the number of liquid droplets required can be determined according to the desired pattern, and if an electrode pair is to be fabricated, the number of liquid droplets obtained is 2.

In the step 3), the thickness of the target material film is 1-10 nanometers, preferably 5 nanometers; the thickness of the polystyrene film is 700 nanometers to 10 microns, preferably 1 micron; the weight of the polystyrene The average molecular weight is 10,000-1,000,000, preferably 200,000; the target material is a material that can be combined with the substrate in step 1), preferably graphene oxide or chromium; in the step of soaking in water, the time is 30 minutes to 3 hours, Preferably 90 minutes; the methods for preparing the film of the target material and the polystyrene film are spin coating or thermal evaporation; in the spin coating, the rotating speed is 3000-8000 rpm, preferably 4000 rpm ; In the thermal evaporation method, the vacuum degree is less than 4×10 ^-4 Pascal, and the evaporation rate is 1 angstrom/second. In this peeling step, since the target material and the substrate have a strong bonding ability, during peeling, the target material film covered on the substrate exposed by the patterning in step 2) is not peeled off, and the films in the remaining areas are all covered. peeled off, thus completing the patterning of the target material.

The method for patterning the material further includes the following step: before the step 1), cleaning the substrate with detergent, water, deionized water, ethanol and acetone respectively.

Electrodes prepared according to the above method, especially electrodes made of graphene or chromium, and the application of the method in preparing electrodes also belong to the protection scope of the present invention. The thickness of the electrode is 1-10 nanometers, and the channel length is 1-100 micrometers.

Since graphene oxide is used as an electrode, it needs to restore its conductivity to graphene through reduction, so the above-mentioned electrode composed of graphene is the graphene oxide patterned according to the above method, annealed or added The method of reducing agent will reduce graphene oxide to obtain it. This method is a conventional method, and various commonly used methods for reducing graphene oxide are applicable. For example, in the annealing method, the degree of vacuum can be 8×10 ^-4 -1× 10 ^-5 Pa, preferably less than 4×10 ^-4 Pa, the temperature can be 400-500°C, preferably 450°C, and the time can be 1-4 hours, preferably 2 hours.

In addition, the application of the electrodes provided by the present invention in the preparation of organic field effect transistors also belongs to the protection scope of the present invention.

The invention discloses for the first time a method for directly preparing graphene oxide on a silicon dioxide substrate by using inkjet printing technology and a stripping method; the thickness of the graphene electrode prepared by the invention is controllable, the channel length of the electrode is controllable, and the The minimum track length can reach 2 microns; the graphene electrode does not need to be transferred, and can be directly used for the preparation of field effect transistors on the silicon dioxide substrate; this method is not limited to the patterning of graphene materials, other Materials with strong bonding capabilities, such as chromium, can also be patterned with this method.

Description of drawings

Fig. 1 is step 2), 3), 5), 6) the optical microscope photo of substrate after finishing;

Fig. 2 is the atomic force microscope photo of the graphene electrode prepared by embodiment 1;

Fig. 3 is the scanning micrograph of the graphene electrode prepared by the present invention;

Fig. 4 is the device curve that the graphene electrode in embodiment 1 is applied in the organic field effect transistor;

5 is a scanning electron micrograph of the metal chromium electrode in Example 2.

Detailed ways

The present invention will be further described below in conjunction with specific examples, but the present invention is not limited to the following examples. The methods are conventional methods unless otherwise specified. The materials can be obtained from public commercial sources unless otherwise specified.

Example 1, preparing graphene electrodes on a silicon dioxide substrate and demonstrating its application in organic field effect transistors.

1) Clean the silica substrate:

Silicon wafers with a thickness of 300 nanometers of silicon dioxide on the surface were ultrasonically cleaned with detergent, water, deionized water, acetone and ethanol for 5 minutes each, and then dried;

2) Place the silicon wafer that has been processed in step 1) on the rotor of a desktop homogenizer, and add dropwise a drop of N,N-dimethylformamide with a weight-average molecular weight of 200,000 and a concentration of 1.5 mg/mL of polyacrylonitrile. solution, adjust the speed of the homogenizer at 3500 rpm, and form a uniform polyacrylonitrile polymer film on the silicon wafer with a thickness of 2 nanometers;

3) Inkjet printing patterned polyacrylonitrile mask layer:

Place the silicon wafer prepared in step 2) with a mask layer on the surface of the inkjet printer (jetlab II inkjetprinting equipment) on the console, control the temperature of the console to 80 ° C, and drip the ink on the surface of the silicon wafer with the inkjet printer For N, N-dimethylformamide solvent, the nozzle of the selected printer is 30 microns, the distance between adjacent droplets is 87 microns, and the pattern consists of two adjacent droplets.

Figure 1a is the pattern formed on the surface of polyacrylonitrile after the droplet dries up; as can be seen from the figure, the ring formed on the edge of the solvent droplet has a width far smaller than the diameter of the droplet itself, which makes the printer's electrode channel area The resolution ability has been greatly improved.

4) On the surface of the patterned silicon wafer obtained in step 3), spin-coat (rotating at a speed of 4000 rpm) an aqueous graphene oxide solution three times to prepare a graphene oxide film with a thickness of 5 nanometers.

Figure 1b is an optical microscope photo after the graphene oxide film is prepared; it can be seen from the figure that graphene oxide is easier to deposit on the exposed silicon dioxide substrate due to the strong bonding force between graphene oxide and silicon dioxide substrate parts.

5) Spin-coat (rotating speed is 4000 rpm) polystyrene film with a thickness of 1 micron on the graphene oxide film obtained in step 4), then put the substrate into water for 90 minutes, and peel off the polystyrene film with tweezers Thin films and thin films of all target materials except circle patterns and polymer films to complete the patterning of graphene oxide.

Figure 1c is the graphene oxide pattern obtained after peeling off the polystyrene polymer film; it can be seen from the figure that the graphene oxide pattern and the polyacrylonitrile pattern have a good complementary relationship, which proves that there is a good transfer between the patterns efficiency.

6) In order to restore the conductivity of the obtained patterned graphene oxide so that it can be used as an electrode, the substrate with the graphene oxide pattern is placed in a vacuum, and when the degree of vacuum is lower than 4×10 ^-4 Pascal, heat it to 450 °C, keep for 2 hours to obtain patterned graphene.

Figure 1d is an optical microscope photo of the reduced graphene electrode after step 6) thermal annealing reduction.

Fig. 2 is the atomic force microscope photo of the reduced graphene electrode after step 6).

Fig. 3 is a scanning electron micrograph of the reduced graphene electrode after step 6).

It can be seen from the figure that the channel length of the graphene electrode is 1-2 microns.

Utilize this embodiment to prepare gained graphene to prepare organic field effect transistor:

A layer of pentacene semiconductor film was prepared on the surface of the obtained graphene electrode prepared in this embodiment by thermal evaporation. During the evaporation process, the vacuum degree was lower than 4 × 10 ^-4 Pascals, and the evaporation rate was 1 angstrom per second, and obtained based on Pentacene organic field effect transistor.

Tested in air with a Keithley 4200 semiconductor tester. Fig. 4a is the obtained transfer curve of the organic field effect transistor, and Fig. 4b is the obtained output curve of the organic field effect transistor.

It can be seen from the figure that the transfer and output curves are still good when the electrode channel is very short.

Example 2. Chromium is patterned on a silicon dioxide substrate using inkjet printing and lift-off process

1) Clean the silica substrate:

Silicon wafers with a thickness of 300 nanometers of silicon dioxide on the surface were ultrasonically cleaned with detergent, water, deionized water, acetone and ethanol for 5 minutes each, and then dried;

2) Place the silicon wafer that has been processed in step 1) on the rotor of a desktop homogenizer, and add dropwise a drop of N,N-dimethylformamide with a weight-average molecular weight of 200,000 and a concentration of 1.5 mg/mL of polyacrylonitrile. solution, adjust the speed of the homogenizer at 3500 rpm, and form a uniform polyacrylonitrile polymer film on the silicon wafer with a thickness of 1 nanometer;

3) Inkjet printing patterned polyacrylonitrile mask layer:

Place the silicon wafer with polyacrylonitrile polymer film on the surface obtained in step 2) on the console of an inkjet printer, control the temperature of the console to 80°C, and drop N,N-dimethylformaldehyde on the surface of the silicon wafer with an inkjet printer For the amide solvent, the nozzle of the selected printer is 30 microns, the distance between adjacent droplets is 87 microns, and the number of droplets is 2 drops.

4) Under the condition that the degree of vacuum is less than 4×10 ^-4 Pascal and the evaporation rate is 1 angstrom/second, a chromium layer with a thickness of 5 nanometers is evaporated on the polyacrylonitrile mask layer by thermal evaporation.

5) Spin-coat one deck (rotating speed is 4000 rev/min) polystyrene macromolecular films with a thickness of 1 micron on the chromium layer obtained in step 4), then put the substrate into water for 90 minutes, and peel off the polystyrene with tweezers Thin films and thin films of all target materials except circle patterns and polymer films, complete the patterning of chromium materials.

Figure 5 is a scanning electron micrograph of patterned chromium electrodes on a silicon wafer with silicon dioxide on its surface. It can be seen that the channel length of the obtained chromium electrode is 2 microns, which has good uniformity.

Claims (12)

1. the patterning method of a material, comprise the steps:

1) preparation one deck macromolecule membrane in substrate;

2) in described step 1) gained macromolecule membrane surface utilizes the good solvent of the described macromolecule membrane of method coating of spray ink Printing, obtains the macromolecule membrane after patterning;

3) in described step 2) on macromolecule membrane after the gained patterning and after the described substrate surface that exposes prepares the film and one deck polystyrene film of one deck target material successively, peel described polystyrene film off after Yu Shuizhong soaks and except pattern film and the described macromolecule membrane of all target materials, complete the patterning of described material.

2. method according to claim 1 is characterized in that: described step 1), described substrate is that quartz plate, silicon chip or surface are with the silicon chip of silicon dioxide layer; The material that consists of described macromolecule membrane is polyacrylonitrile, polystyrene or polymethylmethacrylate; The thickness of described macromolecule membrane is the 1-100 nanometer;

Described step 2) in the method for spray ink Printing, the shower nozzle of ink-jet printer is 20 microns to 100 microns; The adjacent drops spacing is the 120-70 micron; Service temperature is 30-100 ℃; The good solvent of described macromolecule membrane is selected from least a in DMF, toluene and chlorobenzene;

Described step 3) in, the thickness of described target material film is the 1-10 nanometer; The thickness of described polystyrene film is 700 nanometers to 10 micron; The weight-average molecular weight of described polystyrene is 10000-1000000; Described target material be can with step 1) the described substrate material of being combined; Institute is set forth in water in soaking step, and the time is 30 minutes to 3 hours.

3. method according to claim 1 and 2 is characterized in that: the method for preparing macromolecule membrane described step 1) is spin-coating method;

Described step 3) in, the film of the described target material of preparation and the method for polystyrene film are spin-coating method or hot vapour deposition method.

4. method according to claim 3 is characterized in that: described step 1) in described spin-coating method, rotating speed is 2000-5000 rev/min;

Described step 3) in described spin-coating method, rotating speed is 3000-8000 rev/min; In described hot evaporation coating method, vacuum tightness is less than 4 * 10 ^-4Pascal, evaporation rate was 1 dust/second.

5. method according to claim 4, it is characterized in that: the patterning method of described material also comprises the steps: in described step 1) before, described substrate is cleaned up with washing composition, water, deionized water, ethanol and acetone respectively.

6. method according to claim 5, it is characterized in that: described step 1), in described silicon chip with silicon dioxide layer, the thickness of described silicon dioxide layer is the 100-500 nanometer; The material that consists of described macromolecule membrane is the polyacrylonitrile of 10000-1000000; The thickness of described macromolecule membrane is 2 nanometers;

Described step 2) in the method for spray ink Printing, the shower nozzle of ink-jet printer is 30 microns; The adjacent drops spacing is 87 microns; Service temperature is 80 ℃; The good solvent of described macromolecule membrane is DMF;

Described step 3) in, the thickness of described target material film is 5 nanometers; The thickness of described polystyrene film is 1 micron; The weight-average molecular weight of described polystyrene is 200000; Described target material is graphene oxide or chromium; Institute is set forth in water in soaking step, and the time is 90 minutes;

Described step 1) in described spin-coating method, rotating speed is 3500 rev/mins;

Described step 3) in described spin-coating method, rotating speed is 4000 rev/mins; In described hot evaporation coating method, vacuum tightness is less than 4 * 10 ^-4Pascal, evaporation rate was 1 dust/second.

7. method according to claim 6, it is characterized in that: described step 1), in described silicon chip with silicon dioxide layer, the thickness of described silicon dioxide layer is 300 nanometers; The material that consists of described macromolecule membrane is 200000 polyacrylonitrile.

8. the application of the arbitrary described method of claim 1-7 in the preparation electrode.

9. the arbitrary described method of claim 1-7 prepares the electrode of gained.

10. electrode according to claim 9 is characterized in that: the material that consists of described electrode is Graphene or chromium; The thickness of described electrode is the 1-10 nanometer, and channel length is the 1-100 micron.

11. the application of the described electrode of claim 9 in being prepared with field effect transistors.

12. the application of the described electrode of claim 10 in being prepared with field effect transistors.

Images