CN104934329B - Preparation method for ZnO-Thin Film Transistor (ZnO-TFT) based on flexible substrate material - Google Patents

Abstract

The invention relates to a preparation method for a ZnO-TFT based on a flexible substrate material, and belongs to the technical field of microelectronics. The method comprises that a hard substrate and a flexible substrate are cleaned, blown dry and dried, the substrates are bonded, a grid material is deposited, an insulating layer material is deposited, a ZnO channel layer material is deposited, and source and drain electrodes are deposited. The preparation method has the advantages that preparation can be carried out at room temperature, technology is easy to implement and low in cost, and the method can be applied to the field of flexible display technology.

Description

A preparation method of zinc oxide thin film transistor based on flexible substrate material

technical field

The invention belongs to the technical field of microelectronics, and in particular relates to a method for preparing a zinc oxide thin film transistor (ZnO-Thin Film Transistor, ZnO-TFT) based on a flexible substrate material.

Background technique

At present, flexible display has become an important direction for future development due to its excellent performance characteristics such as ultra-thin, light weight, power saving, and foldable. Fabrication of thin-film transistors (TFTs) based on flexible material substrates is a key step in the realization of flexible functional devices. Compared with hard substrate materials such as silicon and glass, flexible thin film transistors are based on flexible materials such as plastics, which can be bent, wound, and folded at a certain angle. Applied in the field of display, it can be rolled into cylinders and other shapes, and reduced in size to be put into the pockets of clothes worn by people. It has strong practical significance and good market prospects.

Among them, zinc oxide is characterized by its lower growth temperature, better chemical stability, and lower preparation cost, especially because of its high direct wide band gap (band gap at room temperature is 3.37eV), and its thin film material is transparent and stable under visible light, etc. It has become a research hotspot in the field of thin film transistor fabrication on flexible substrates.

Zinc oxide thin film transistors have many advantages: high stability in the visible light region, high field effect mobility, low device fabrication temperature, high current switching ratio, low threshold voltage and high transmittance in the visible light region. After the thin film transistor, a new type of display driving device with great development potential in the field of display driving in the future.

Contents of the invention

The invention provides a method for preparing a zinc oxide thin film transistor based on a flexible substrate material to solve the problems of bending and warping of the flexible substrate material during the growth of the thin film material and device preparation.

The technical scheme that the present invention takes is: comprise the following steps:

(1) cleaning, drying, and drying of hard substrate and flexible substrate; the hard substrate material is glass, silicon wafer, or stainless steel sheet, and the flexible substrate material is polyimide PI;

(2) substrate bonding, the substrate bonding material is photoresist;

(3) gate material deposition, the gate material is aluminum, prepared by electron beam evaporation method EB;

(4) deposition of insulating layer material, the insulating layer material is SiO ₂ , grown by plasma enhanced chemical vapor deposition PECVD, Plasma Enhanced Chemical Vapor Deposition method;

(5) Zinc oxide channel layer material is deposited, and described channel layer material is ZnO, and method adopts radio frequency magnetron sputtering;

(6) Deposition of source and drain electrodes, the material of the source and drain electrodes is aluminum, and the photolithography lift-off technique is used, and the deposition method adopts vacuum evaporation and electron beam evaporation.

The step (1) cleans the hard substrate, 25mm*25mm and the flexible substrate polyimide 2, 20mm*20mm respectively, the method is:

(1) First put it into an acetone solution and ultrasonically clean it at room temperature for 4-6 minutes to remove surface molecular contamination, etc.;

(2) Then place it in an ethanol solution and ultrasonically clean it for 3-5 minutes at room temperature to remove residual acetone on the surface;

(3) Ultrasonic cleaning with deionized water at room temperature for 3-5 minutes to remove residual ethanol and ionic contamination;

(4) Blow dry with high-purity nitrogen, and dry in an oven at 90°C for 3-5 minutes.

The step (2) substrate bonding includes: fixing the hard substrate on the glue homogenizer, dripping photoresist 1, 0.2ml-0.5ml in the middle of the hard substrate, lining the cleaned flexible material Bottom polyimide, placed on the photoresist one, after the glass substrate and the flexible substrate are fully contacted through the photoresist one, start the homogenizer, the speed is 450-550 rpm, and the time is 30 seconds-120 seconds , so that the photoresist is evenly spread between the flexible substrate and the hard substrate, so that the flexible substrate and the hard substrate are tightly bonded together, and the flexible substrate is fixed flat on the surface of the hard substrate, Form sample one.

The step (3) gate material deposition includes: put the sample 1 into the growth chamber of the electron beam evaporation device, place the flexible substrate downward, and use the electron beam evaporation method to plate aluminum on the flexible substrate as the gate 4 , after completion, put it into acetone solution, ethanol, and deionized water for ultrasonic cleaning for 3-5 minutes, rinse with deionized water, and blow dry with _N2 . During this process, the photoresist is dissolved in acetone solution, thereby , the hard substrate is separated from other parts. Form sample two.

The step (4) of insulating layer material deposition includes: taking a 4-inch clean silicon wafer, placing sample 2 on the middle position above the silicon wafer, sample 2 is adsorbed on the surface of the silicon wafer, and placing the silicon wafer with sample 2 on PECVD growth chamber base. In order to avoid curling and warping of the sample 2 during the deposition process of the insulating layer, which will affect the growth of the insulating layer, a mold 1 made of a cleaned stainless steel sheet is taken. The mold 1 is a square frame with an inner diameter of 15 mm and a frame width of 5 mm. Mold 1 is pressed on sample 2, and a silicon dioxide insulating layer is deposited downward to form sample 3.

The step (5) of depositing the zinc oxide channel layer material includes placing sample 3 into acetone, ethanol, and deionized water for 3-5 minutes, followed by ultrasonic cleaning for 3-5 minutes, then rinsing with deionized water, blowing dry with N ₂ , and drying Dry it in an oven at 90°C for 3-5 minutes, place it on the sputtering table tray of the magnetron sputtering instrument, press mold 2 on it, the inner diameter is 12mm, which is 3mm smaller than the inner dimension of mold 1, and the frame width is 10mm. It is fixed on the tray of the sputtering table, hangs the tray, deposits the zinc oxide channel layer, takes it out from the tray, and obtains sample 4.

The step (6) source-drain electrode deposition includes,

(1) Cleaning, according to the cleaning method described in step (1), sample four is cleaned;

(2) Fixing, according to the bonding method described in step (2), utilize photoresist 2 to fix sample 4 after cleaning on the hard substrate surface, form sample 5;

(3) Photolithography-stripping method, the channel layer is etched out a plurality of small island regions for making a single thin film transistor device, the source and drain electrode regions are etched on the channel layer in the small island region, and the source and drain electrode regions are etched. The source and drain electrodes are deposited in the drain electrode area, as follows:

①Glue coating, fix sample 5 on the glue homogenizer, rotate, and coat photoresist 3 with inversion characteristics, the speed is 500-1300 rpm, and the time is 3-5 minutes, so that the photoresist is evenly coated on the the surface of the channel layer;

②Pre-bake, pre-bake at 90°C and harden the film for 9 minutes;

③ Exposure, cover with photolithography plate 14, place it under the exposure machine for exposure, at this time, the covered part of the pattern is not exposed to light, and the rest is exposed;

④Development, put it in the developer solution, the photoresist three corresponding to the exposed part is dissolved in the developer solution, is removed, and zinc oxide is exposed;

⑤ Corrosion, corroding with one-thousandth hydrochloric acid, the part not protected by the photoresist, that is, the zinc oxide part is corroded, exposing the insulating layer of silicon dioxide, forming sample 6;

⑥Remove glue, put sample 6 into acetone, ethanol, deionized water and ultrasonically clean it for 3-5 minutes in sequence, photoresist 2 and 3 are dissolved in acetone and stripped off;

7. Secondary photolithography, according to the bonding method described in step (2), utilize photoresist 4 to fix sample 6 after cleaning and deglue on the hard substrate surface;

Glue coating, according to the method described in step 1., spin-coating photoresist five with inversion characteristics;

Pre-bake, pre-bake at 90°C, harden the film for 9 minutes;

Expose, cover with photolithography plate 2 17, after the plate is aligned, the graphics overlap with zinc oxide, and look down;

Baking after exposure, heating at 110°C for 9 minutes, the photoresist with inversion characteristics becomes a negative resist five times;

naked exposure;

Developing, put it into the developer solution, the unexposed part of the negative film is dissolved by the developer solution, and the exposed part remains;

Rinse with deionized water to form sample 7 to obtain the area where the source and drain electrodes are about to be deposited;

⑧ Deposit source and drain electrodes, according to the bonding method described in step 2, fix sample 7 on the hard substrate, put it into the electron beam evaporation equipment EB, and deposit the source/drain electrode metal aluminum;

⑨Remove the glue, soak in acetone solution for 1 hour to 2 hours, ultrasonic for 2-3 minutes, the photoresist 4 dissolves in acetone and the hard substrate is separated, and the photoresist 5 on the surface of the channel layer together with the electrodes on it It was removed by acetone to expose the channel layer, rinsed with ethanol and deionized water, and dried with N ₂ gas.

The invention has the advantages that it can be prepared at room temperature, has simple and easy process and low cost, and can be applied in the technical field of flexible display.

Description of drawings

Fig. 1 is a schematic diagram of dropping photoresist on a hard substrate;

Fig. 2 is the schematic diagram of flexible material substrate polyimide PI;

Fig. 3 is a sectional view of a sample;

Figure 4.1 is a schematic diagram of depositing gate aluminum on sample 1;

Figure 4.2 is a schematic diagram of the structure of sample 2;

Figure 5.1 is a top view of the second product placed on the silicon wafer;

Figure 5.2 is a cross-sectional view of sample 2 placed on the silicon wafer;

Figure 6.1 is a three-dimensional schematic diagram of the mold;

Figure 6.2 is a top view of the mold;

Figure 7.1 is a top view of a silicon dioxide insulating layer prepared to be deposited using a mold;

Figure 7.2 is a cross-sectional view of preparing to deposit a silicon dioxide insulating layer using mold one;

Figure 8 is a three top view of the sample;

Figure 9 is a three-sectional view of the sample;

Figure 10.1 is a top view of the zinc oxide channel layer prepared to be deposited using the second mold;

Figure 10.2 is a cross-sectional view of the zinc oxide channel layer prepared for deposition using the second mold;

Fig. 11 is a top view of deposited zinc oxide channel layer;

Fig. 12 is a sample four sectional view;

Figure 13.1 is a top view of sample 5;

Figure 13.2 is a cross-sectional view of sample five;

Fig. 14 is a schematic diagram of a photolithography plate;

Figure 15.1 is a top view of sample six;

Figure 15.2 is a cross-sectional view of sample six;

Figure 16.1 is a cross-sectional view of a plurality of small island regions where a single thin film transistor device is produced by etching the channel layer;

Figure 16.2 is a top view of a plurality of small island regions where a single thin film transistor device is produced by etching the channel layer;

Fig. 17 is a schematic diagram of photolithography plate 2;

Figure 18.1 is the top view of the second pair of photolithographic plates;

Figure 18.2 is a cross-sectional view of the second pair of photolithography plates, which is a schematic diagram of the preparation area of a single device;

Figure 19 is a cross-sectional view of sample seven, which is a schematic diagram of the preparation area of a single device;

Figure 20.1 is a top view of a device structure based on a flexible substrate zinc oxide thin film transistor, a schematic diagram of a single device;

Figure 20.2 is a cross-sectional view of a device structure based on a flexible substrate zinc oxide thin film transistor, and a schematic diagram of a single device.

detailed description

Example 1

Include the following steps:

(1) cleaning, drying, and drying of hard substrate and flexible substrate; the hard substrate material is glass, silicon wafer, or stainless steel sheet, and the flexible substrate material is polyimide PI;

Clean the hard substrate 1, 25mm*25mm and the flexible substrate polyimide 2, 20mm*20mm respectively, the method is:

(1) First put it into an acetone solution and ultrasonically clean it for 4 minutes at room temperature to remove surface molecular contamination, etc.;

(2) Then place it in an ethanol solution and ultrasonically clean it for 3 minutes at room temperature to remove residual acetone on the surface;

(3) Ultrasonic cleaning with deionized water at room temperature for 5 minutes to remove residual ethanol and ionic contamination;

(4) blow dry with high-purity nitrogen, and dry at 90° C. for 5 minutes in an oven;

(2) substrate bonding, the substrate bonding material is photoresist;

Fix the hard substrate on the homogenizer, drop 0.2ml of photoresist-3 in the middle of the hard substrate, as shown in Figure 1, put the cleaned flexible material substrate polyimide 2, such as As shown in Figure 2, place it on the photoresist one, and after the glass substrate and the flexible substrate are fully contacted through the photoresist one, start the homogenizer, the speed is 450 rpm, and the time is 30 seconds, so that the photoresist one Spread evenly between the flexible substrate and the hard substrate, so that the flexible substrate and the hard substrate are tightly bonded together, and the flexible substrate is flattened on the surface of the hard substrate to form sample 1, sample 1 The section view is shown in Figure 3;

(3) gate material deposition, the gate material is aluminum Al, prepared by electron beam evaporation method EB, Electron-beam Evaporation;

Put the sample 1 into the growth chamber of the electron beam evaporation device with the flexible substrate facing down, and use the electron beam evaporation method to plate aluminum on the flexible substrate as the grid 4, as shown in Figure 4.1. Put it into acetone solution, ethanol, and deionized water for ultrasonic cleaning for 3 minutes, rinse with deionized water, and blow dry with _N2 . During this process, the photoresist is dissolved in the acetone solution, so that the hard substrate and other parts Separated to form sample 2, as shown in Figure 4.2;

(4) deposition of insulating layer material, the insulating layer material is SiO ₂ , grown by plasma enhanced chemical vapor deposition PECVD, Plasma Enhanced Chemical Vapor Deposition method;

Take a 4-inch clean silicon wafer 5, place sample 2 on the middle position above the silicon wafer, sample 2 is adsorbed on the surface of the silicon wafer, as shown in Figure 5.1 and 5.2, place the silicon wafer with sample 2 on the base of the PECVD growth chamber, In order to avoid curling and warping of the sample 2 during the deposition process of the insulating layer, which would affect the growth of the insulating layer, a mold 6 made of cleaned stainless steel sheets was taken. The mold 1 was in the shape of a square frame with an inner diameter of 15 mm and a frame width of 5 mm. As shown in Figures 6.1 and 6.2, mold one is pressed on sample two, and the top view and section effects are shown in Figures 7.1 and 7.2, and a silicon dioxide insulating layer 7 is deposited, and the top view is shown in Figure 8, forming sample three and sample three The cross-sectional view is shown in Figure 9;

(5) Zinc oxide channel layer material deposition, the channel layer material is ZnO, the method adopts radio-frequency magnetron sputtering radio-frequency magnetron sputtering, RF-sputtering;

Put sample three into acetone, ethanol, and deionized water for 3 minutes, then rinse with deionized water, blow dry with _N2 , dry in a drying oven at 90°C for 3 minutes, and place it in a magnetron sputtering apparatus. On the tray 8 of the sputtering table, press mold 2 9 on it. The inner diameter is 12mm, which is 3mm smaller than the inner dimension of mold 1, and the frame width is 10mm. Fix it on the tray of the sputtering table with screws 10, as shown in Figure 10.1 and 10.2 Top view, schematic sectional view, hang the tray, deposit the zinc oxide channel layer 11, the top view is shown in Figure 11, after the process is completed, it is taken out from the tray to obtain sample 4, and Figure 12 is a sectional view of sample 4;

(6) Source-drain electrode deposition, the source-drain electrode material is Al, using photolithography stripping technology, the deposition method adopts vacuum evaporation and electron beam evaporation;

(1) Cleaning, according to the cleaning method described in step (1), sample four is cleaned;

(2) Fixing, according to the bonding method described in step (2), use photoresist 2 12 to fix the cleaned sample 4 on the surface of the hard substrate to form sample 5, as shown in Figures 13.1 and 13.2 for the top view of sample 5, section view;

(3) Photolithography-stripping method, the channel layer is etched out a plurality of small island regions for making a single thin film transistor device, the source and drain electrode regions are etched on the channel layer in the small island region, and the source and drain electrode regions are etched. The source and drain electrodes are deposited in the drain electrode area, as follows:

①Glue coating, fix sample 5 on the glue homogenizer, rotate, and coat photoresist 3 13 with inversion characteristics, the rotation speed is 500 rpm, and the time is 3 minutes, so that the photoresist is evenly coated on the channel layer s surface;

②Pre-bake, pre-bake at 90°C and harden the film for 9 minutes;

③ Exposure, covered with photolithography plate 14 as shown in Figure 14, placed under the exposure machine for exposure, at this time, the covered part of the pattern was not exposed to light, and the rest was exposed;

④Development, put it in the developer solution, the photoresist three corresponding to the exposed part is dissolved in the developer solution, is removed, and zinc oxide is exposed;

⑤ Corrosion, corroding with one-thousandth hydrochloric acid, the part not protected by the photoresist, that is, the zinc oxide part is corroded, exposing the insulating layer of silicon dioxide, forming sample 6, as shown in Figure 15.1 small island and sample 15.2 ;

⑥Remove the glue, put sample 6 into acetone, ethanol, and deionized water, and ultrasonically clean it for 3-5 minutes in sequence. A small island area for making a single thin film transistor device;

7. Secondary photolithography, according to the bonding method described in step (2), utilize photoresist 4 15 to fix sample 6 after cleaning and deglue on the hard substrate surface;

Glue coating, according to the method described in step 1., spin-coating photoresist 5 16 with inversion characteristics;

Pre-bake, pre-bake at 90°C, harden the film for 9 minutes;

Expose, cover with the photolithography plate 2 17 shown in Figure 17, after the plate is aligned, the graphics overlap with the zinc oxide, and the top view and cross-section are shown in Figures 18.1 and 18.2;

Baking after exposure, heating at 110°C for 9 minutes, the photoresist with inversion characteristics becomes a negative resist five times;

naked exposure;

Developing, put it into the developer solution, the unexposed part of the negative film is dissolved by the developer solution, and the exposed part remains;

Rinse with deionized water to form sample 7, and obtain the area where the source and drain electrodes are about to be deposited. Figure 19 is a schematic diagram corresponding to the preparation of a single thin film transistor device;

⑧ Deposit source and drain electrodes, according to the bonding method described in step 2, fix sample 7 on the hard substrate, put it into the electron beam evaporation equipment EB (Electron-beam Evaporation), and deposit the source/drain electrode metal aluminum 18 ;

⑨Remove the glue, soak in acetone solution for 1 hour, ultrasonic for 2 minutes, the photoresist 4 is dissolved in acetone and the hard substrate is separated, and the photoresist 5 on the surface of the channel layer and the electrodes on it are removed by acetone, exposing The channel layer was rinsed with ethanol and deionized water, and dried with N ₂ gas to complete the device preparation. The top view and cross-section of the device are shown in Figures 20.1 and 20.2.

Example 2

Include the following steps:

(1) cleaning, drying, and drying of hard substrate and flexible substrate; the hard substrate material is glass, silicon wafer, or stainless steel sheet, and the flexible substrate material is polyimide PI;

Clean the hard substrate 1, 25mm*25mm and the flexible substrate polyimide 2, 20mm*20mm respectively, the method is:

(1) First put it into an acetone solution and ultrasonically clean it for 5 minutes at room temperature to remove surface molecular contamination, etc.;

(2) Then place it in an ethanol solution and ultrasonically clean it for 4 minutes at room temperature to remove residual acetone on the surface;

(3) Ultrasonic cleaning with deionized water at room temperature for 4 minutes to remove residual ethanol and ionic contamination;

(4) blow dry with high-purity nitrogen, and dry at 90°C for 4 minutes in a drying oven;

(2) substrate bonding, the substrate bonding material is photoresist;

Fix the hard substrate on the homogenizer, drop 0.35ml of photoresist-3 in the middle of the hard substrate, as shown in Figure 1, put the cleaned flexible material substrate polyimide 2, such as As shown in Figure 2, put it on the photoresist one, and after the glass substrate and the flexible substrate are fully contacted through the photoresist one, start the homogenizer, the speed is 500 rpm, and the time is 75 seconds, so that the photoresist one Spread evenly between the flexible substrate and the hard substrate, so that the flexible substrate and the hard substrate are tightly bonded together, and the flexible substrate is flattened on the surface of the hard substrate to form sample 1, sample 1 The section view is shown in Figure 3;

(3) gate material deposition, the gate material is aluminum, prepared by electron beam evaporation method EB, Electron-beamEvaporation;

Put the sample 1 into the growth chamber of the electron beam evaporation device with the flexible substrate facing down, and use the electron beam evaporation method to plate aluminum on the flexible substrate as the grid 4, as shown in Figure 4.1. Put it into acetone solution, ethanol, and deionized water for ultrasonic cleaning for 4 minutes, rinse with deionized water, and blow dry with _N2 . During this process, the photoresist is dissolved in the acetone solution, so that the hard substrate and other parts Separated to form sample 2, as shown in Figure 4.2;

(4) deposition of insulating layer material, the insulating layer material is SiO ₂ , grown by plasma enhanced chemical vapor deposition PECVD, Plasma Enhanced Chemical Vapor Deposition method;

Take a 4-inch clean silicon wafer 5, place sample 2 on the middle position above the silicon wafer, sample 2 is adsorbed on the surface of the silicon wafer, as shown in Figure 5.1 and 5.2, place the silicon wafer with sample 2 on the base of the PECVD growth chamber, In order to avoid curling and warping of the sample 2 during the deposition process of the insulating layer, which would affect the growth of the insulating layer, a mold 6 made of cleaned stainless steel sheets was taken. The mold 1 was in the shape of a square frame with an inner diameter of 15 mm and a frame width of 5 mm. As shown in Figures 6.1 and 6.2, mold one is pressed on sample two, and the top view and section effects are shown in Figures 7.1 and 7.2, and a silicon dioxide insulating layer 7 is deposited, and the top view is shown in Figure 8, forming sample three and sample three The cross-sectional view is shown in Figure 9;

(5) Zinc oxide channel layer material deposition, the channel layer material is ZnO, the method adopts radio-frequency magnetron sputtering radio-frequency magnetron sputtering, RF-sputtering;

Put sample three into acetone, ethanol, and deionized water for 4 minutes, then rinse with deionized water, blow dry with _N2 , and dry in a drying oven at 90°C for 4 minutes, then place it in a magnetron sputtering apparatus On the tray 8 of the sputtering table, press mold 2 9 on it. The inner diameter is 12mm, which is 3mm smaller than the inner dimension of mold 1, and the frame width is 10mm. Fix it on the tray of the sputtering table with screws 10, as shown in Figure 10.1 and 10.2 Top view, schematic sectional view, hang the tray, deposit the zinc oxide channel layer 11, the top view is shown in Figure 11, after the process is completed, it is taken out from the tray to obtain sample 4, and Figure 12 is a sectional view of sample 4;

(6) Source-drain electrode deposition, the source-drain electrode material is Al, using photolithography stripping technology, the deposition method adopts vacuum evaporation and electron beam evaporation;

(1) Cleaning, according to the cleaning method described in step (1), sample four is cleaned;

(2) Fixing, according to the bonding method described in step (2), use photoresist 2 12 to fix the cleaned sample 4 on the surface of the hard substrate to form sample 5, as shown in Figures 13.1 and 13.2 for the top view of sample 5, section view;

(3) Photolithography-stripping method, the channel layer is etched out a plurality of small island regions for making a single thin film transistor device, the source and drain electrode regions are etched on the channel layer in the small island region, and the source and drain electrode regions are etched. The source and drain electrodes are deposited in the drain electrode area, as follows:

①Glue coating, fix sample 5 on the glue homogenizer, rotate, and coat the photoresist 3 13 with inversion characteristics, the rotation speed is 900 rpm, and the time is 3-5 minutes, so that the photoresist is evenly coated on the groove the surface of the road layer;

②Pre-bake, pre-bake at 90°C and harden the film for 9 minutes;

③ Exposure, covered with photolithography plate 14 as shown in Figure 14, placed under the exposure machine for exposure, at this time, the covered part of the pattern was not exposed to light, and the rest was exposed;

④Development, put it in the developer solution, the photoresist three corresponding to the exposed part is dissolved in the developer solution, is removed, and zinc oxide is exposed;

⑤ Corrosion, corroding with one-thousandth hydrochloric acid, the part not protected by the photoresist, that is, the zinc oxide part is corroded, exposing the insulating layer of silicon dioxide, forming sample 6, as shown in Figure 15.1 small island and sample 15.2 ;

⑥Remove the glue, put the sample 6 into acetone, ethanol, and deionized water and ultrasonically clean it for 4 minutes in sequence, and the photoresist 2 and 3 are dissolved in acetone and stripped off, as shown in Figure 16.1 and 16.2. The island region of a single TFT device;

7. Secondary photolithography, according to the bonding method described in step (2), utilize photoresist 4 15 to fix sample 6 after cleaning and deglue on the hard substrate surface;

Glue coating, according to the method described in step 1., spin-coating photoresist 5 16 with inversion characteristics;

Pre-bake, pre-bake at 90°C, harden the film for 9 minutes;

Expose, cover with the photolithography plate 2 17 shown in Figure 17, after the plate is aligned, the graphics overlap with the zinc oxide, and the top view and cross-section are shown in Figures 18.1 and 18.2;

Baking after exposure, heating at 110°C for 9 minutes, the photoresist with inversion characteristics becomes a negative resist five times;

naked exposure;

Developing, put it into the developer solution, the unexposed part of the negative film is dissolved by the developer solution, and the exposed part remains;

Rinse with deionized water to form sample 7, and obtain the area where the source and drain electrodes are about to be deposited. Figure 19 is a schematic diagram corresponding to the preparation of a single thin film transistor device;

⑧ Deposit source and drain electrodes, according to the bonding method described in step 2, fix sample 7 on the hard substrate, put it into the electron beam evaporation equipment EB (Electron-beam Evaporation), and deposit the source/drain electrode metal aluminum 18 ;

⑨Remove the glue, soak in acetone solution for 1.5 hours, ultrasonic for 2.5 minutes, the photoresist 4 is dissolved in acetone and the hard substrate is separated, and the photoresist 5 on the surface of the channel layer and the electrodes on it are removed by acetone, exposing The channel layer was rinsed with ethanol and deionized water, and dried with N ₂ gas to complete the device preparation. The top view and cross-section of the device are shown in Figures 20.1 and 20.2.

Example 3

Include the following steps:

(1) cleaning, drying, and drying of hard substrate and flexible substrate; the hard substrate material is glass, silicon wafer, or stainless steel sheet, and the flexible substrate material is polyimide PI;

Clean the hard substrate 1, 25mm*25mm and the flexible substrate polyimide 2, 20mm*20mm respectively, the method is:

(1) First put it into an acetone solution and ultrasonically clean it for 6 minutes at room temperature to remove surface molecular contamination, etc.;

(2) Then place it in an ethanol solution and ultrasonically clean it for 5 minutes at room temperature to remove residual acetone on the surface;

(3) Ultrasonic cleaning with deionized water at room temperature for 5 minutes to remove residual ethanol and ionic contamination;

(4) blow dry with high-purity nitrogen, and dry at 90° C. for 5 minutes in an oven;

(2) substrate bonding, the substrate bonding material is photoresist;

Fix the hard substrate on the homogenizer, drop photoresist 1, 0.5ml in the middle of the hard substrate, as shown in Figure 1, and clean the flexible material substrate polyimide 2, such as As shown in Figure 2, place it on the photoresist one, and after the glass substrate and the flexible substrate are fully contacted through the photoresist one, start the homogenizer, the speed is 550 rpm, and the time is 120 seconds, so that the photoresist one Spread evenly between the flexible substrate and the hard substrate, so that the flexible substrate and the hard substrate are tightly bonded together, and the flexible substrate is flattened on the surface of the hard substrate to form sample 1, sample 1 The section view is shown in Figure 3;

(3) gate material deposition, the gate material is aluminum, prepared by electron beam evaporation method EB, Electron-beamEvaporation;

Put the sample 1 into the growth chamber of the electron beam evaporation device with the flexible substrate facing down, and use the electron beam evaporation method to plate aluminum on the flexible substrate as the grid 4, as shown in Figure 4.1. Put it into acetone solution, ethanol, and deionized water for ultrasonic cleaning for 5 minutes, rinse with deionized water, and blow dry with _N2 . During this process, the photoresist is dissolved in acetone solution, so that the hard substrate and other parts Separated to form sample 2, as shown in Figure 4.2;

(4) deposition of insulating layer material, the insulating layer material is SiO ₂ , grown by plasma enhanced chemical vapor deposition PECVD, Plasma Enhanced Chemical Vapor Deposition method;

Take a 4-inch clean silicon wafer 5, place sample 2 on the middle position above the silicon wafer, sample 2 is adsorbed on the surface of the silicon wafer, as shown in Figure 5.1 and 5.2, place the silicon wafer with sample 2 on the base of the PECVD growth chamber, In order to avoid curling and warping of the sample 2 during the deposition process of the insulating layer, which would affect the growth of the insulating layer, a mold 6 made of cleaned stainless steel sheets was taken. The mold 1 was in the shape of a square frame with an inner diameter of 15 mm and a frame width of 5 mm. As shown in Figures 6.1 and 6.2, mold one is pressed on sample two, and the top view and section effects are shown in Figures 7.1 and 7.2, and a silicon dioxide insulating layer 7 is deposited, and the top view is shown in Figure 8, forming sample three and sample three The cross-sectional view is shown in Figure 9;

(5) Zinc oxide channel layer material deposition, the channel layer material is ZnO, the method adopts radio-frequency magnetron sputtering radio-frequency magnetron sputtering, RF-sputtering;

Put sample three into acetone, ethanol, and deionized water for 5 minutes, then rinse with deionized water, blow dry with _N2 , and dry in a drying oven at 90°C for 5 minutes, then place it in a magnetron sputtering apparatus On the tray 8 of the sputtering table, press mold 2 9 on it. The inner diameter is 12mm, which is 3mm smaller than the inner dimension of mold 1, and the frame width is 10mm. Fix it on the tray of the sputtering table with screws 10, as shown in Figure 10.1 and 10.2 Top view, schematic sectional view, hang the tray, deposit the zinc oxide channel layer 11, the top view is shown in Figure 11, after the process is completed, it is taken out from the tray to obtain sample 4, and Figure 12 is a sectional view of sample 4;

(6) Source-drain electrode deposition, the source-drain electrode material is Al, using photolithography stripping technology, the deposition method adopts vacuum evaporation and electron beam evaporation;

(1) Cleaning, according to the cleaning method described in step (1), sample four is cleaned;

(2) Fixing, according to the bonding method described in step (2), use photoresist 2 12 to fix the cleaned sample 4 on the surface of the hard substrate to form sample 5, as shown in Figures 13.1 and 13.2 for the top view of sample 5, section view;

(3) Photolithography-stripping method, the channel layer is etched out a plurality of small island regions for making a single thin film transistor device, the source and drain electrode regions are etched on the channel layer in the small island region, and the source and drain electrode regions are etched. The source and drain electrodes are deposited in the drain electrode area, as follows:

①Glue coating, fix sample 5 on the homogenizer, rotate it, and coat the photoresist 3 13 with inversion characteristics, the rotation speed is 1300 rpm, and the time is 5 minutes, so that the photoresist is evenly coated on the channel layer s surface;

②Pre-bake, pre-bake at 90°C and harden the film for 9 minutes;

③ Exposure, covered with photolithography plate 14 as shown in Figure 14, placed under the exposure machine for exposure, at this time, the covered part of the pattern was not exposed to light, and the rest was exposed;

④Development, put it in the developer solution, the photoresist three corresponding to the exposed part is dissolved in the developer solution, is removed, and zinc oxide is exposed;

⑤ Corrosion, corroding with one-thousandth hydrochloric acid, the part not protected by the photoresist, that is, the zinc oxide part is corroded, exposing the insulating layer of silicon dioxide, forming sample 6, as shown in Figure 15.1 small island and sample 15.2 ;

⑥Remove the glue, put the sample 6 into acetone, ethanol, and deionized water, and ultrasonically clean it for 5 minutes in sequence. The island region of a single TFT device;

7. Secondary photolithography, according to the bonding method described in step (2), utilize photoresist 4 15 to fix sample 6 after cleaning and deglue on the hard substrate surface;

Glue coating, according to the method described in step 1., spin-coating photoresist 5 16 with inversion characteristics;

Pre-bake, pre-bake at 90°C, harden the film for 9 minutes;

Expose, cover with the photolithography plate 2 17 shown in Figure 17, after the plate is aligned, the graphics overlap with the zinc oxide, and the top view and cross-section are shown in Figures 18.1 and 18.2;

Baking after exposure, heating at 110°C for 9 minutes, the photoresist with inversion characteristics becomes a negative resist five times;

naked exposure;

Developing, put it into the developer solution, the unexposed part of the negative film is dissolved by the developer solution, and the exposed part remains;

Rinse with deionized water to form sample 7, and obtain the area where the source and drain electrodes are about to be deposited. Figure 19 is a schematic diagram corresponding to the preparation of a single thin film transistor device;

⑧ Deposit source and drain electrodes, according to the bonding method described in step 2, fix sample 7 on the hard substrate, put it into the electron beam evaporation equipment EB (Electron-beam Evaporation), and deposit the source/drain electrode metal aluminum 18 ;

⑨Remove the glue, soak in acetone solution for 2 hours, ultrasonic for 3 minutes, the photoresist 4 is dissolved in acetone and the hard substrate is separated, the photoresist 5 on the surface of the channel layer and the electrodes on it are removed by acetone, exposing The channel layer was rinsed with ethanol and deionized water, and dried with N ₂ gas to complete the device preparation. The top view and cross-section of the device are shown in Figures 20.1 and 20.2.

Claims (4)

1. a kind of preparation method based on flexible substrate material zinc oxide thin-film transistor, it is characterised in that comprise the following steps：

（One）The cleaning of hard substrates and flexible substrate, dry up, dry；The hard backing material is glass, silicon chip or stainless Steel disc, the flexible substrate material are polyimides（PI）；

（Two）Substrate is bonded, and the substrate jointing material is photoresist；

The substrate bonding includes：Hard substrates are fixed on spin coating instrument, photoresist one are dripped in hard substrates centre position, 0.2ml 0.5ml, cleaned flexible material substrate polyimides are placed in above photoresist one, treat hard substrates with flexibility Substrate starts spin coating instrument after photoresist one is all contacted, and 450 550 revs/min of rotating speed, makes 120 seconds 30 seconds time Photoresist one is uniformly layered between flexible substrate and hard substrates, so that flexible substrate is tightly bonded in one with hard substrates Rise, flexible substrate is flattened and is fixed on hard substrates surface, form sample one；

（Three）Gate material deposition, the grid material are aluminum, are prepared using electron beam evaporation method；

The gate material deposition includes：Sample one is put in apparatus for electron beam evaporation growth room, placement direction is flexible liner Down, deposited by electron beam evaporation method is aluminized on flexible substrates as grid at bottom（4）, after the completion of, it is molten that acetone is put it into successively It is cleaned by ultrasonic 3-5 minutes in liquid, ethanol, deionized water, deionized water is rinsed, N₂Dry up, in the process, photoresist one Acetone soln is dissolved in, so as to hard substrates come with being separately from other sections, and form sample two；

（Four）Insulating layer material is deposited, and the insulating layer material is silicon dioxide, strengthens chemical vapor deposition side using gas ions Method grows；

The insulating layer material deposition includes：4 inches of clean silicon wafers are taken, sample two is placed on into centre position above silicon chip, sample Product two are adsorbed in silicon chip surface, the silicon chip with sample two are placed in PECVD growth rooms base, for avoiding insulating layer deposition process Middle sample two is heated and curling, rake angle phenomenon occurs, and affects insulating layer growth, takes mould made by the stainless steel substrates for cleaning up One, mould one is square frame-shaped, and internal diameter 15mm, frame width 5mm be pressed in mould one above sample two, deposits silicon dioxide insulating layer, It is sample three to define the product after silicon dioxide layer；

（Five）Zinc-oxide channel layer material is deposited, and the channel layer materials are Zinc Oxide, and method adopts rf magnetron sputtering；

（Six）Source-drain electrode is deposited, and the source-drain electrode materials are aluminum, and using lithography stripping technology, deposition process is steamed using vacuum Plating, electron beam evaporation.

2. a kind of preparation method based on flexible substrate material zinc oxide thin-film transistor according to claim 1, which is special Levy and be：The step（One）By hard substrates, 25mm*25mm and flexible substrate polyimides（2）, 20mm*20mm is respectively clearly Wash, method is：

（1）First hard substrates or flexible substrate are put in acetone soln and are cleaned by ultrasonic at room temperature 6 minutes 4 minutes, removed Surface molecular type stains；

（2）It is cleaned by ultrasonic in being subsequently placed in ethanol solution at room temperature 35 minutes, removes surface residual acetone；

（3）Deionized water is cleaned by ultrasonic 35 minutes at room temperature again, removes residual ethanol and ion-type stains；

（4）High pure nitrogen is dried up, and is dried 35 minutes at 90 DEG C of drying oven.

3. a kind of preparation method based on flexible substrate material zinc oxide thin-film transistor according to claim 1, which is special Levy and be：The step（Five）Zinc-oxide channel layer material is deposited to be included, sample three is respectively put into acetone, ethanol, deionization It is cleaned by ultrasonic 3-5 minutes in water successively, then deionized water is rinsed, N₂Dry up, be dried 35 minutes at 90 DEG C of drying oven, will Which is placed on the sputtering unit pallet of magnetic control sputtering device, top die tool two, and internal diameter is 12mm, less than one inside dimension 3mm of mould, frame width For 10mm, it is fixed on sputtering unit pallet with screw, hangs pallet, which is taken from pallet by depositing zinc oxide channel layer Go out, obtain sample four.

4. a kind of preparation method based on flexible substrate material zinc oxide thin-film transistor according to claim 3, which is special Levy and be：The step（Six）Source-drain electrode is deposited to be included,

（1）Cleaning, according to step（One）The cleaning method, sample four is cleaned；

（2）It is fixed, according to step（Two）Sample four after cleaning is fixed on hard lining using photoresist two by the adhesive bonding method Basal surface, forms sample five；

（3）Photoetching-stripping means, etches multiple island regions for making single film transistor device channel layer, little Source, drain regions are etched on channel layer in the region of island, it is in source, drain regions sedimentary origin, drain electrode, specific as follows：

1. gluing, sample five is fixed on spin coating instrument, and rotation scribbles the photoresist three of reverse speed characterisstic, and rotating speed 500-1300 turns/ Minute, 35 minutes time, make photoresist three be uniformly coated on the surface of channel layer；

2. front baking, front baking, post bake 9 minutes at 90 DEG C；

3. expose, covered with reticle one, be positioned under exposure machine and expose, now, figure covering part is not affected by illumination, remaining Partial exposure；

4. develop, be placed in developer solution, the corresponding photoresist of exposed portion three is dissolved in developer solution, is removed, exposes oxidation Zinc；

5. corrode, the part of glue protection is not photo-etched with one thousandth hcl corrosion, be i.e. zinc oxide portion is corroded, expose absolutely Edge layer silicon dioxide, forms sample six；

6. remove photoresist, sample six is put in acetone, ethanol, deionized water and is cleaned by ultrasonic 3-5 minutes successively, photoresist two, three is molten In acetone so as to being stripped；

7. secondary photoetching, according to step（Two）The adhesive bonding method, will clean six fixation of sample after removing photoresist using photoresist four On hard substrates surface；

Gluing, according to step 1. methods described, spin coating has the photoresist five of reverse speed characterisstic；

Front baking, front baking at 90 DEG C, post bake 9 minutes；

Exposure, with reticle two（17）Cover, after version, two each regional graphics of photolithography plate are Chong Die with Zinc Oxide；

Exposure after bake, heats 9 minutes at 110 DEG C, and the photoresist five for having reverse speed characterisstic becomes negative glue；

Naked exposure；

Development, is put in developer solution, bears the developed liquid of glue unexposed portion and dissolves away, and exposed portion retains；

Deionized water is rinsed, and forms sample seven, and obtaining will sedimentary origin, the region of drain electrode；

8. sedimentary origin, drain electrode, according to step（Two）The adhesive bonding method, sample seven is fixed in hard substrates, electricity is put into In beamlet evaporation equipment, sedimentary origin, drain metal aluminum；

9. remove photoresist, be put into acetone soln and soak 2 hours 1 hour, ultrasonic 2-3 minutes, photoresist four is dissolved in acetone so as to hard Substrate is separated off, and channel layer surface photoresist five is removed by acetone together with source thereon, drain metal aluminum, exposes raceway groove Layer, then clean, the N with ethanol, deionized water rinsing₂Air-blowing is done.