A method of fabricating a thin film transistor on a zein protein substrate

Abstract

The application discloses a method for preparing a thin film transistor on a corn protein substrate, which comprises the following steps: firstly, preparing a semiconductor device on a graphene / copper foil substrate with good heat resistance; then, dropping and coating a solution of a degradable substrate material on the device; and after the solvent is evaporated, peeling off the protein substrate film from the copper foil, so that a degradable p-type transient thin film transistor device can be obtained on the protein film. The application overcomes the limitation of the heat resistance of the substrate material on the preparation temperature of the device, meanwhile, avoids the damage of the solution environment to the protein substrate during the preparation of the device, and improves the performance of the device.

Description

Technical Field

[0001] This invention relates to the field of semiconductor device technology, and more specifically, to a method for fabricating thin-film transistors on a corn protein substrate. Background Technology

[0002] Traditional silicon-based electronic devices are robust and durable, but everything has two sides. Their excessive robustness limits their application in certain specialized fields. For example, in the medical field, after traditional devices are implanted and their treatment or monitoring tasks are completed, a second surgery is required to remove them, damaging healed tissue, causing significant pain for the patient, and increasing the risk of postoperative complications. In the military field, if traditional devices fall into enemy hands, they are easily compromised, leading to the leakage of classified information. However, the emergence of biodegradable transient electronic devices in recent years can effectively solve these problems. Transient electronic devices are generally composed of biodegradable substrate materials, semiconductor functional materials, and electrode materials. After the fabricated electronic functional device has performed its designated function, its physical form and function can completely or partially disappear under external stimuli. This emerging electronic device has a very broad application prospect in biomedicine, information security, and environmental protection.

[0003] Electronic devices are diverse, and transistors are among the most important core components. Currently, some researchers have successfully fabricated transient transistor devices on biodegradable polymer or protein substrates. Despite these successes, fabricating electronic devices on protein substrates remains challenging. Firstly, protein substrates typically have poor heat resistance, with decomposition temperatures generally not exceeding 200°C. For semiconductor material growth, higher temperatures are beneficial for improving crystallinity, reducing defects, and thus enhancing device performance. Due to the limitations of the substrate material's heat resistance, the fabrication process temperature for biodegradable transient devices must be lower than the substrate material's decomposition temperature, severely impacting semiconductor device performance. Secondly, protein substrates have poor resistance to acids / alkalis and organic solvents. Semiconductor device fabrication often involves treatment with acids / alkalis, organic solvents, or plasma; these harsh conditions can damage the protein substrate and consequently the semiconductor device. Some material systems can achieve good performance at relatively low preparation temperatures. For example, n-type AZO-TFTs, TZO-TFTs, and AZTO-TFTs can achieve good performance at room temperature. However, some materials still require high-temperature processes to achieve ideal performance, such as p-type oxides. SnO-TFTs, in particular, require annealing at 200–300°C, and Cu... xO-TFTs require annealing at 500°C. Therefore, the poor heat resistance of biodegradable substrate materials severely limits the application of semiconductor materials and devices requiring high-temperature processes in the field of biodegradable devices. Furthermore, minimizing or preventing contact between protein substrates and acids / alkalis and solvents during device fabrication is another challenging problem. Summary of the Invention

[0004] The purpose of this invention is to design and develop a method for fabricating thin-film transistors on a corn protein substrate, enabling the semiconductor material and device to achieve higher processing temperatures that exceed the heat resistance limits of biodegradable substrate materials. This effectively avoids damage to the protein substrate from the solution environment during device fabrication, thereby improving device performance.

[0005] The technical solution provided by this invention is as follows:

[0006] A method for fabricating thin-film transistors on a corn protein substrate includes the following steps:

[0007] Step 1: Deposit a gate electrode on the graphene surface of a graphene / copper foil substrate to obtain the first sample;

[0008] Step 2: Sputter and deposit an insulating layer on the first sample to obtain the second sample;

[0009] Step 3: Cover the second sample with the first mask and sputter to deposit the active layer to obtain the third sample;

[0010] Step 4: Cover the third sample with a second mask, and deposit source and drain electrodes by vapor deposition to obtain the fourth sample;

[0011] Step 5: Anneal the fourth sample at 150–500°C for 10–60 min to obtain the fifth sample;

[0012] Step 6: Prepare a protein solution and coat it onto the surface of the fifth sample. After the solvent in the protein solution evaporates naturally, the sixth sample is obtained.

[0013] The preparation process of the protein solution is as follows:

[0014] Weigh the following raw materials:

[0015] 5-20g corn gluten meal, 5-50ml deionized water, 10-100ml ethanol;

[0016] After the raw materials are mixed and dissolved, they are placed in a water bath at 50-80°C and heated for 5-30 minutes. After cooling to room temperature, the protein solution is obtained.

[0017] Step 7: Remove the copper foil substrate from the sixth sample to obtain a p-type thin film transistor.

[0018] Preferably, the motor material of the gate electrode is Al or Ag.

[0019] Preferably, the thickness of the gate electrode is 50–200 nm.

[0020] Preferably, the insulating layer is made of HfO2.

[0021] Preferably, in step two, the sputtering power is 100–250 W, the temperature is 25–200 °C, the pressure is 3–20 mtorr, the Ar / O2 ratio is 9:1–2:1, the deposition time is 50–150 min, and the film thickness is 50–200 nm.

[0022] Preferably, the active layer material is SnO.

[0023] Preferably, the sputtering deposition process in step three is as follows:

[0024] SnO material was obtained by reactive sputtering using a metal Sn target. The sputtering power was 15–70 W, the temperature was room temperature, the pressure was 3–20 mtorr, the Ar / O2 ratio was 9:1–2:1, the deposition time was 5–30 min, and the thickness of the active layer was 20–150 nm.

[0025] Preferably, the source and drain electrodes are made of Au, and the thickness of the source and drain electrodes is 50-100 nm.

[0026] Preferably, the distance between the source and drain electrodes is 10 μm to 1 mm.

[0027] The beneficial effects of this invention are as follows:

[0028] This invention presents a method for fabricating thin-film transistors on a corn protein substrate. This method enables the fabrication of devices requiring high-temperature processing on substrates with poor heat resistance, overcoming the limitation of device fabrication temperature caused by the heat resistance of the substrate material. This is beneficial for improving device performance. At the same time, it avoids the damage to the protein substrate caused by the solution environment during device fabrication, making it possible to fabricate transient electronic devices requiring high-temperature processing on a biodegradable substrate. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the structure of the first sample according to the present invention.

[0030] Figure 2 This is a schematic diagram of the structure of the second sample according to the present invention.

[0031] Figure 3 This is a schematic diagram of the structure of the first mask of the present invention.

[0032] Figure 4 This is a schematic diagram of the structure of the third sample described in this invention.

[0033] Figure 5 This is a schematic diagram of the structure of the second mask of the present invention.

[0034] Figure 6 This is a schematic diagram of the structure of the fourth sample described in this invention.

[0035] Figure 7 This is a schematic diagram of the structure of the sixth sample described in this invention.

[0036] Figure 8 This is a schematic diagram of the structure of the p-type thin-film transistor described in this invention.

[0037] Figure 9 This is a curve comparing the on / off ratio of the device prepared in the embodiment of the present invention with that of the device prepared in the comparative example. Detailed Implementation

[0038] The present invention will now be described in further detail so that those skilled in the art can implement it based on the description.

[0039] This invention provides a method for fabricating thin-film transistors on a corn protein substrate. First, a semiconductor device is fabricated on a heat-resistant graphene / copper foil substrate using high-temperature processes. Then, a biodegradable protein solution is drop-coated onto the device. After the solvent evaporates, the protein substrate film is peeled off from the copper foil, thus obtaining a biodegradable p-type transient thin-film transistor device on the protein film. Furthermore, during device fabrication, the biodegradable substrate film does not come into contact with the solvent environment, preventing damage to the protein substrate film caused by the solvent. The specific steps include:

[0040] Step 1, such as Figure 1 As shown, gate electrode 130 is deposited:

[0041] The graphene 120 / copper foil substrate 110 was placed in an electron beam evaporation (EB) apparatus, and a gate electrode 130 was deposited on the surface of the graphene 120 to obtain the first sample.

[0042] The gate electrode 130 is made of Al or Ag, and its thickness ranges from 50 to 200 nm.

[0043] Step Two, as follows Figure 2 As shown, insulating layer 140 is deposited:

[0044] The first sample was placed in an RF magnetron sputtering apparatus to deposit an insulating layer 140, thereby obtaining the second sample;

[0045] The insulating layer 140 is made of HfO2. The HfO2 insulating layer material is obtained by sputtering with a ceramic HfO2 target. The sputtering power is 100-250W, the temperature is 25-200℃, the pressure is 3-20mtorr, the Ar / O2 ratio is 9:1-2:1, the deposition time is 50-150min, and the film thickness is 50-200nm.

[0046] Step 3: Deposition of the active layer 150:

[0047] like Figure 3 As shown, a first mask with an active layer 150 pattern is placed over the second sample, and the second sample covered with the first mask is placed in an RF magnetron sputtering apparatus to deposit the active layer 150. Figure 4 As shown, a third sample was obtained;

[0048] The active layer 150 is made of SnO. A metal Sn target is used to obtain SnO material through reactive sputtering. The sputtering power is 15-70W, the temperature is room temperature, the pressure is 3-20mtorr, the Ar / O2 ratio is 9:1-2:1, the deposition time is 5-30min, and the film thickness is 20-150nm.

[0049] Step 4: Deposition of source and drain electrodes at 160°:

[0050] like Figure 5 As shown, a second mask with a source / drain electrode pattern 160 is placed over the third sample and then placed in a thermal evaporation stage to deposit the source / drain electrode 160. Figure 6 As shown, the fourth sample was obtained;

[0051] The source / drain electrode 160 is made of Au and has a thickness of 50–100 nm.

[0052] The distance between the source and drain electrodes 160 is the channel length of the transistor device. Depending on the requirements, the channel length can be different, ranging from 10 μm to 1 mm.

[0053] Step 5: Anneal the active layer at 150°C:

[0054] The fourth sample was placed in a rapid annealing furnace and annealed at 150–500°C for 10–60 min to obtain the fifth sample.

[0055] Step Six, as Figure 7 As shown, a protein solution was prepared and coated onto the surface of the fifth sample. After the solvent in the protein solution evaporated naturally, a protein film 170 was formed on the surface of the device, thus obtaining the sixth sample.

[0056] The preparation process of the protein solution is as follows:

[0057] Weigh the following raw materials:

[0058] 5-20g corn gluten meal, 5-50ml deionized water, 10-100ml ethanol;

[0059] The raw materials are placed in a flask and mixed. The mixture is stirred with a glass rod until the corn gluten powder is fully dissolved. The flask is then placed in a water bath at 50–80°C and heated for 5–30 minutes. After being removed and cooled to room temperature, the protein solution is obtained.

[0060] Step 7, as follows Figure 8 As shown, remove the copper foil substrate:

[0061] Because the interlayer forces of graphene are very weak, the copper foil substrate 110 on the sixth sample can be directly peeled off to obtain a biodegradable p-type SnO thin film transistor on the corn protein substrate.

[0062] Example

[0063] Step 1: Place the graphene / copper foil substrate in an electron beam evaporation (EB) device and deposit an Ag gate electrode on the graphene surface with an electrode thickness of 100 nm to obtain the first sample.

[0064] Step 2: Place the first sample in an RF magnetron sputtering apparatus to deposit an insulating layer and obtain the second sample;

[0065] The insulating layer is made of HfO2. The HfO2 insulating layer material is obtained by sputtering with a ceramic HfO2 target. The sputtering power is 150W, the temperature is 25℃, the pressure is 8mtorr, the Ar / O2 ratio is 9:1, the deposition time is 120min, and the film thickness is 200nm.

[0066] Step 3: Cover the second sample with the first mask patterned with the active layer, and place the second sample covered with the first mask in the radio frequency magnetron sputtering equipment to perform active layer deposition to obtain the third sample;

[0067] The active layer is made of SnO, which is obtained by reactive sputtering using a metal Sn target. The sputtering power is 15W, the temperature is room temperature, the pressure is 5mtorr, the Ar / O2 ratio is 9:1, the deposition time is 5min, and the film thickness is 30nm.

[0068] Step 4: Cover the third sample with the second mask template with the source and drain electrode pattern, and place it in the thermal evaporation stage to deposit the source and drain electrodes to obtain the fourth sample.

[0069] The source and drain electrodes are made of Au and have a thickness of 50 nm.

[0070] The channel length is 30 μm;

[0071] Step 5: Place the fourth sample in a rapid annealing furnace and anneal at 300℃ for 30 minutes to obtain the fifth sample;

[0072] Step 6: Prepare a protein solution and coat it onto the surface of the fifth sample. After the solvent in the protein solution evaporates naturally, a protein film is formed on the surface of the device to obtain the sixth sample.

[0073] The preparation process of the protein solution is as follows:

[0074] Weigh the following raw materials:

[0075] 5g corn gluten powder, 5ml deionized water, 15ml ethanol;

[0076] The raw materials were placed in a flask and mixed. The mixture was stirred with a glass rod until the corn gluten powder was fully dissolved. The flask was then placed in a water bath at 75°C and heated for 15 minutes. After being removed and cooled to room temperature, the protein solution was obtained.

[0077] Step 7: Since the interlayer forces of graphene are very weak, the copper foil substrate on the sixth sample can be directly peeled off to obtain a biodegradable p-type SnO thin film transistor on the corn protein substrate.

[0078] Comparative Example

[0079] Step 1: Prepare the protein solution:

[0080] Weigh 5g of corn gluten powder, 5ml of deionized water, and 15ml of ethanol, place them in a flask and mix. Stir with a glass rod until the gluten powder is fully dissolved. Place the flask in a water bath at 75°C and heat for 15 minutes. Remove and cool to room temperature to obtain a protein solution.

[0081] Step 2: Preparation of protein substrate film:

[0082] Take a flat PET plastic sheet, drop the prepared protein solution onto the PET plastic sheet, and after the solvent evaporates naturally, the protein film dries and detaches from the plastic sheet to obtain a biodegradable protein substrate film.

[0083] Step 3: Place the protein substrate film in an electron beam evaporation (EB) device to deposit an Ag film as a gate electrode with a thickness of 100 nm.

[0084] Step 4: Place the protein substrate coated with the gate electrode in an RF magnetron sputtering apparatus to deposit an insulating layer material;

[0085] The insulating layer is made of HfO2. The HfO2 insulating layer material is obtained by sputtering with a ceramic HfO2 target. The sputtering power is 150W, the temperature is 25℃, the pressure is 8mtorr, the Ar / O2 ratio is 9:1, the deposition time is 120min, and the film thickness is 200nm.

[0086] Step 5: Cover the insulating layer with a mask containing the active layer pattern and place it in an RF magnetron sputtering device to deposit the active layer material. The active layer material is SnO, and a metal Sn target is used to obtain the SnO material through reactive sputtering. The sputtering power is 15W, the temperature is room temperature, the pressure is 5mtorr, the Ar / O2 ratio is 9:1, the deposition time is 5min, and the film thickness is 30nm.

[0087] Step 6: Cover the active layer with a mask template containing the source and drain electrode patterns, and place it in a thermal evaporation stage to deposit the source and drain electrode materials. The electrode material used is Au, with a thickness of 50 nm and a channel length of 30 μm.

[0088] Step 7: Place the device in a rapid annealing furnace and anneal it at 100°C for 100 minutes to obtain the comparison device.

[0089] The biodegradable p-type SnO thin-film transistor prepared in the examples was compared with the TFT device prepared on a protein substrate in the comparative examples. The difference between the comparative and examples is that each layer of the device (gate electrode, insulating layer, active layer, source / drain electrode) is directly deposited on the corn protein substrate. Therefore, due to the heat resistance of the protein substrate, the annealing conditions were annealed at 50–100°C for 10–100 min. Figure 9 The figure shows a comparison of device transfer curves. It can be seen that the device prepared in the example achieves an on / off ratio of 10. 4 In contrast, the source and drain currents of the comparative devices hardly change with the gate voltage because they cannot reach the ideal annealing temperature. In other words, the channel layer carrier concentration is not controlled by the gate voltage, and the devices do not have the characteristics of thin-film transistors.

[0090] This invention presents a method for fabricating thin-film transistors on a corn protein substrate, which makes it possible to fabricate devices that require high-temperature processing on substrates with poor heat resistance. This overcomes the limitation of device fabrication temperature caused by the heat resistance of the substrate material, improves the electrical performance of the device, and avoids damage to the protein substrate by the solution environment during device fabrication. This makes it possible to fabricate transient electronic devices that require high-temperature processing.

[0091] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and embodiments shown and described herein.

Claims

1. A method for fabricating thin-film transistors on a corn protein substrate, characterized in that, Includes the following steps: Step 1: Deposit a gate electrode on the graphene surface of a graphene / copper foil substrate to obtain the first sample; Step 2: Sputter and deposit an insulating layer on the first sample to obtain the second sample; Step 3: Cover the second sample with the first mask and sputter to deposit the active layer to obtain the third sample; Step 4: Cover the third sample with a second mask, and deposit source and drain electrodes by vapor deposition to obtain the fourth sample; Step 5: Anneal the fourth sample at 150–500°C for 10–60 min to obtain the fifth sample; Step 6: Prepare a protein solution and coat it onto the surface of the fifth sample. After the solvent in the protein solution evaporates naturally, the sixth sample is obtained. The preparation process of the protein solution is as follows: Weigh the following raw materials: 5-20g corn gluten meal, 5-50ml deionized water, 10-100ml ethanol; After the raw materials are mixed and dissolved, they are placed in a water bath at 50-80°C and heated for 5-30 minutes. After cooling to room temperature, the protein solution is obtained. Step 7: Remove the copper foil substrate from the sixth sample to obtain a p-type thin-film transistor; In this case, because the interlayer forces of graphene are very weak, the copper foil substrate on the sixth sample was directly peeled off.

2. The method for fabricating thin-film transistors on a corn protein substrate as described in claim 1, characterized in that, The motor material of the gate electrode is Al or Ag.

3. The method for fabricating thin-film transistors on a corn protein substrate as described in claim 2, characterized in that, The thickness of the gate electrode is 50–200 nm.

4. The method for fabricating thin-film transistors on a corn protein substrate as described in claim 1, characterized in that, The insulating layer is made of HfO2.

5. The method for fabricating thin-film transistors on a corn protein substrate as described in claim 4, characterized in that, In step two, the sputtering power is 100~250W, the temperature is 25~200℃, the pressure is 3~20mtorr, the Ar / O2 ratio is 9:1~2:1, the deposition time is 50~150min, and the film thickness is 50~200nm.

6. The method for fabricating thin-film transistors on a corn protein substrate as described in claim 1, characterized in that, The active layer material is SnO.

7. The method for fabricating thin-film transistors on a corn protein substrate as described in claim 6, characterized in that, The sputtering deposition process in step three is as follows: SnO material was obtained by reactive sputtering using a metal Sn target. The sputtering power was 15~70W, the temperature was room temperature, the pressure was 3~20mtorr, the Ar / O2 ratio was 9:1~2:1, the deposition time was 5~30min, and the thickness of the active layer was 20~150nm.

8. The method for fabricating thin-film transistors on a corn protein substrate as described in claim 7, characterized in that, The source and drain electrodes are made of Au, and the thickness of the source and drain electrodes is 50~100nm.

9. The method for fabricating thin-film transistors on a corn protein substrate as described in claim 8, characterized in that, The distance between the source and drain electrodes is 10 μm to 1 mm.

Images