Thin film transistor, display panel and display terminal

Abstract

The invention relates to a thin film transistor, a display panel and a display terminal. The thin film transistor comprises an active part, and the active part comprises a first channel part, a first contact part and a second contact part which are arranged at the two ends of the first channel part, a first functional part arranged between the first channel part and the first contact part, and a second functional part arranged between the first channel part and the second contact part; wherein the resistance of the first function part is smaller than that of the second function part. The resistance of the first function part is set to be smaller than that of the second function part, the second contact part is electrically connected with the drain electrode of the thin film transistor, and the resistance of the second function part is large, so that the drain electrode potential barrier can be increased, the leakage current between the second function part and the drain electrode is reduced, and the off-state leakage current is reduced.

Description

[0001] This application claims priority to Chinese patent application No. 202510833185.2, filed on June 19, 2025, the entire contents of which are incorporated herein by reference. TECHNICAL FIELD

[0002] The present application relates to the technical field of display, in particular to a thin film transistor, a display panel and a display terminal. BACKGROUND

[0003] The channel length of sub-micron channel thin film transistor is in the interval of 0.1 microns to 1 micron, which is the key stage of the transition from traditional channel size to nanometer technology. Shorter channel length not only can significantly improve the switching speed of thin film transistor and greatly reduce power consumption, but also provides the possibility for realizing higher integrated integrated circuits.

[0004] However, as the channel length of sub-micron channel thin film transistor continues to shorten, the influence of drain voltage on source barrier becomes particularly significant under sub-micron scale. This influence causes drain induced barrier lowering (DIBL), thereby leading to an increase in off-state leakage current and affecting the energy efficiency and stability of thin film transistor. SUMMARY

[0005] Embodiments of the present application provide a thin film transistor, a display panel and a display terminal to improve the technical problem of the increase in off-state leakage current of sub-micron channel thin film transistor, which affects the energy efficiency and stability of thin film transistor.

[0006] To achieve the above-mentioned purpose, according to a first aspect of the present application, a thin film transistor is provided, comprising: an active part comprising a first channel part, a first contact part and a second contact part arranged at both ends of the first channel part, a first functional part arranged between the first channel part and the first contact part, and a second functional part arranged between the first channel part and the second contact part; a source electrode and a drain electrode, the source electrode being connected with the first contact part, and the drain electrode being connected with the second contact part; wherein the resistance of the first functional part is smaller than the resistance of the second functional part.

[0007] Optionally, the carrier concentration of the first functional part is greater than the carrier concentration of the second functional part.

[0008] Optionally, the first functional part has a first concentration of donor impurities and a second concentration of acceptor impurities, and the second functional part has a third concentration of donor impurities and a fourth concentration of acceptor impurities.

[0009] Optionally, the absolute value of the first difference between the first concentration and the second concentration is greater than the absolute value of the second difference between the third concentration and the fourth concentration.

[0010] Optionally, both the first difference and the second difference are positive; or, both the first difference and the second difference are negative.

[0011] Optionally, the first concentration is equal to the third concentration, or the second concentration is equal to the fourth concentration.

[0012] Optionally, the active portion further includes a second channel portion stacked with the first channel portion, one end of the second channel portion contacting the first functional portion, and the other end of the second channel portion contacting the second functional portion; The carrier concentration in the second channel is greater than that in the first channel.

[0013] Optionally, the thin-film transistor further includes a gate, which is disposed on the side of the second channel portion opposite to the first channel portion, and the gate is disposed on the same layer as the source and the drain.

[0014] Optionally, the resistance of the first channel portion is greater than the resistance of the second functional portion, the resistance of the first functional portion is greater than the resistance of the first contact portion, and the resistance of the first contact portion is equal to the resistance of the second contact portion.

[0015] According to a second aspect of this application, a display panel is provided, including the thin-film transistors described above.

[0016] According to a third aspect of this application, a display terminal is provided, including the display panel described above.

[0017] In the thin-film transistor of this application embodiment, by setting the resistance of the first functional part to be less than the resistance of the second functional part, the drain is connected to the second contact part. Since the resistance of the second functional part is larger, the drain barrier can be increased, the leakage current between the second functional part and the drain can be reduced, thereby reducing the off-state leakage current.

[0018] Other features and advantages of this application will be described in detail in the following detailed description section. Attached Figure Description To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] To gain a more complete understanding of this application and its beneficial effects, the following description will be provided in conjunction with the accompanying drawings, wherein the same reference numerals in the following description denote the same parts.

[0020] Figure 1 This is a schematic cross-sectional view of a thin-film transistor provided in an exemplary embodiment of this disclosure; Figures 2A to 2H This is a fabrication process diagram of a thin-film transistor provided in an exemplary embodiment of this disclosure; Figure 3 This is a cross-sectional structural diagram of a display panel provided in an exemplary embodiment of this disclosure; Figure 4 This is a schematic diagram of the structure of a display terminal provided in an exemplary embodiment of this disclosure.

[0021] Explanation of reference numerals in the attached figures: 1-Thin-film transistor; 10 - Active part; 11 - First channel part; 12 - First contact part; 16 - Second contact part; 13 - First functional part; 14 - Second functional part; 15 - Second channel part; 20-gate; 30-Source; 40-Drain; 51-Light-shielding layer; 52-Interlayer insulating layer; 53-Gate insulating layer; 54-Passivation layer; 55-Substrate; 56-Buffer layer; 61-Photoresist layer; 611-Nanopillar; 62-First semiconductor layer; 63-Second semiconductor layer; 2-Display panel; 21-Anode; 22-Light-emitting material layer; 23-Cathode; 24-Encapsulation layer; 241-Organic layer; 242-Inorganic layer; 3-Display terminal; 4-Terminal body. Detailed Implementation

[0022] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the protection scope of this application.

[0023] To achieve the above objectives, according to the first aspect of this application, such as Figure 1As shown, a thin-film transistor 1 is provided, including an active portion 10. The active portion 10 includes a first channel portion 11, a first contact portion 12 and a second contact portion 16 disposed at both ends of the first channel portion 11, a first functional portion 13 disposed between the first channel portion 11 and the first contact portion 12, and a second functional portion 14 disposed between the first channel portion 11 and the second contact portion 16; wherein the resistance of the first functional portion 13 is less than the resistance of the second functional portion 14.

[0024] like Figure 1 As shown, the active part 10 includes a first contact part 12, a first functional part 13, a first channel part 11, a second functional part 14, and a second contact part 16 connected in sequence.

[0025] The first channel portion 11 is the channel region of the thin-film transistor 1, serving as the path for the directional movement of charge carriers to form current. Charge carriers include electrons and holes. The length of the first channel portion 11 is the channel length of the thin-film transistor 1. Figure 1 The dimension of the first channel portion 11 in the horizontal direction. The dimension of the first channel portion 11 perpendicular to the current direction is the channel width of the thin-film transistor 1, i.e. Figure 1 The direction perpendicular to the paper.

[0026] The first contact portion 12 is electrically connected to the source 30 of the thin-film transistor 1, and the second contact portion 16 is electrically connected to the drain 40 of the thin-film transistor 1. The source 30 provides charge carriers, which flow to the drain 40 through the first channel portion 11.

[0027] The first functional part 13 is located between the first contact part 12 and the first channel part 11, and the second functional part 14 is located between the second contact part 16 and the first channel part 11. Since the resistance of the first functional part 13 is less than the resistance of the second functional part 14, the drain barrier 40 can be increased, the leakage current between the second functional part 14 and the drain 40 can be reduced, thereby reducing the off-state leakage current.

[0028] In some embodiments, the material of the active part 10 includes amorphous silicon, polycrystalline silicon, metal oxide semiconductor, etc.

[0029] In some embodiments, the first channel portion 11, the first contact portion 12, the second contact portion 16, the first functional portion 13, and the second functional portion 14 are made of the same material. For example, the materials of the first channel portion 11, the first contact portion 12, the second contact portion 16, the first functional portion 13, and the second functional portion 14 are all amorphous silicon, or all polycrystalline silicon, or all metal oxide semiconductor. With the above arrangement, the fabrication process of the active portion 10 can be simplified.

[0030] It should be understood that when the materials of the first channel portion 11, the first contact portion 12, the second contact portion 16, the first functional portion 13, and the second functional portion 14 are the same, the first channel portion 11, the first contact portion 12, the second contact portion 16, the first functional portion 13, and the second functional portion 14 can be formed using the same patterning process. The patterning process includes steps such as coating photoresist, exposure and development, etching, and photoresist removal.

[0031] Optionally, the sheet resistance of the first functional unit 13 is less than the sheet resistance of the second functional unit 14.

[0032] Sheet resistance (R□) refers to the resistance of a square conductive film in the direction of current flow. Sheet resistance is independent of the side length of the square and is determined only by the material's resistivity (ρ) and thickness (t). The formula is: R□ = ρ / t. The unit of sheet resistance is ohms per square sq (Ω / sq). Sheet resistance is also called sheet resistance.

[0033] When the first functional part 13 and the second functional part 14 are formed by the same patterning process, the thickness of the first functional part 13 and the second functional part 14 is the same. At this time, the resistivity of the first functional part 13 is less than the resistivity of the second functional part 14.

[0034] In other embodiments, the thicknesses of the first functional part 13 and the second functional part 14 may be different.

[0035] Optionally, the carrier concentration of the first functional unit 13 is greater than the carrier concentration of the second functional unit 14.

[0036] In some embodiments, the first functional unit 13 and the second functional unit 14 are made of the same material, but the carrier concentrations in the first functional unit 13 and the second functional unit 14 are different. The resistance of the first functional unit 13 and the second functional unit 14 can be adjusted by adjusting the carrier concentration. The carrier concentration is negatively correlated with the sheet resistance. That is, when the carrier concentration in the first functional unit 13 increases, the sheet resistance of the first functional unit 13 decreases; when the carrier concentration in the first functional unit 13 decreases, the sheet resistance of the first functional unit 13 increases. Therefore, by setting the carrier concentration of the first functional unit 13 to be greater than that of the second functional unit 14, the sheet resistance of the first functional unit 13 can be made smaller than that of the second functional unit 14, thereby facilitating the realization that the resistance of the first functional unit 13 is smaller than that of the second functional unit 14.

[0037] It should be noted that charge carriers include electrons and holes. When both the first functional unit 13 and the second functional unit 14 contain only electrons, the electron concentration in the first functional unit 13 is greater than the electron concentration in the second functional unit 14.

[0038] When both the first functional unit 13 and the second functional unit 14 contain only holes, the hole concentration in the first functional unit 13 is greater than the hole concentration in the second functional unit 14.

[0039] When both the first functional unit 13 and the second functional unit 14 contain electrons and holes, the one with the higher concentration is the majority carrier and the one with the lower concentration is the minority carrier. In this case, the carrier concentration is the absolute value of the difference between the majority carrier and minority carrier concentrations. That is, when the electron concentration in the first functional unit 13 is greater than the hole concentration in the first functional unit 13, the carrier concentration of the first functional unit 13 is the difference between the electron and hole concentrations. When the electron concentration in the first functional unit 13 is less than the hole concentration in the first functional unit 13, the carrier concentration of the first functional unit 13 is the difference between the hole and electron concentrations.

[0040] Similarly, when the electron concentration in the second functional unit 14 is greater than the hole concentration in the second functional unit 14, the carrier concentration of the second functional unit 14 is the difference between the electron concentration and the hole concentration. When the electron concentration in the second functional unit 14 is less than the hole concentration in the second functional unit 14, the carrier concentration of the second functional unit 14 is the difference between the hole concentration and the electron concentration.

[0041] Optionally, the first functional unit 13 has a first concentration of donor impurity and a second concentration of acceptor impurity, and the second functional unit 14 has a third concentration of donor impurity and a fourth concentration of acceptor impurity.

[0042] Donor impurities are impurity atoms that, when incorporated into a semiconductor, can provide free electrons (negatively charged carriers). Acceptor impurities are impurity atoms that, when incorporated into a semiconductor, can accept electrons (i.e., provide holes, positively charged carriers).

[0043] In some embodiments, donor impurities include group V elements of the periodic table, such as phosphorus (P), arsenic (As), and antimony (Sb).

[0044] In some embodiments, the acceptor impurity includes elements of group III in the periodic table, such as boron (B) and gallium (Ga).

[0045] It should be noted that donor impurities and acceptor impurities can be formed by doping separately, and this application does not restrict the doping order of donor and acceptor impurities. For example, donor impurities can be doped first, followed by acceptor impurities. Alternatively, acceptor impurities can be doped first, followed by donor impurities.

[0046] Optionally, the absolute value of the first difference between the first concentration and the second concentration is greater than the absolute value of the second difference between the third concentration and the fourth concentration. By setting the absolute value of the first difference to be greater than the absolute value of the second difference, the sheet resistance of the first functional unit 13 can be made smaller than the sheet resistance of the second functional unit 14.

[0047] Optionally, both the first difference and the second difference can be positive; or, both the first difference and the second difference can be negative.

[0048] In some embodiments, both the first and second differences are positive. That is, the first concentration is greater than the second concentration, and the third concentration is greater than the fourth concentration.

[0049] In some embodiments, both the first difference and the second difference are negative. That is to say, the first concentration is less than the second concentration, and the third concentration is less than the fourth concentration.

[0050] Optionally, the first concentration is equal to the third concentration, or the second concentration is equal to the fourth concentration.

[0051] In some embodiments, the first concentration is equal to the third concentration. That is, the first functional portion 13 and the second functional portion 14 can be doped in the same doping process, and after doping, the first concentration of the first functional portion 13 is the same as the third concentration of the second functional portion 14. By setting the second concentration to be different from the fourth concentration, the absolute value of the first difference is made greater than the absolute value of the second difference. With the above setting, the number of doping steps can be reduced, simplifying the fabrication process of the thin-film transistor 1.

[0052] In some embodiments, the second concentration is equal to the fourth concentration. That is, the first functional unit 13 and the second functional unit 14 can be doped in the same doping process, and after doping, the third concentration of the first functional unit 13 is the same as the fourth concentration of the second functional unit 14. By setting the first concentration to be different from the third concentration, the absolute value of the first difference is greater than the absolute value of the second difference. With the above setting, the number of doping steps can be reduced, simplifying the fabrication process of the thin-film transistor 1.

[0053] Optionally, the resistance of the first channel portion 11 is greater than the resistance of the first functional portion 13; and / or, the resistance of the first channel portion 11 is greater than the resistance of the second functional portion 14.

[0054] In some embodiments, the resistance of the first channel portion 11 is greater than the resistance of the first functional portion 13. With the above configuration, the first channel portion 11 can be used as a channel for carrier migration.

[0055] In some embodiments, the resistance of the first channel portion 11 is greater than the resistance of the second functional portion 14. With the above configuration, the first channel portion 11 can be used as a channel for carrier migration.

[0056] In some embodiments, the resistance of the first channel portion 11 is greater than the resistance of the first functional portion 13, and the resistance of the first channel portion 11 is greater than the resistance of the second functional portion 14. With the above configuration, the first channel portion 11 can be used as a channel for carrier migration.

[0057] Optionally, the sheet resistance of the first channel portion 11 is greater than the sheet resistance of the first functional portion 13; and / or, the sheet resistance of the first channel portion 11 is greater than the sheet resistance of the second functional portion 14.

[0058] In some embodiments, the sheet resistance of the first channel portion 11 is greater than the sheet resistance of the first functional portion 13. For example, the first channel portion 11 and the first functional portion 13 may be made of different materials. Alternatively, the first channel portion 11 and the first functional portion 13 may be made of the same material, and different sheet resistances may be achieved by controlling the carrier concentration.

[0059] In some embodiments, the sheet resistance of the first channel portion 11 is greater than the sheet resistance of the second functional portion 14. For example, the first channel portion 11 and the second functional portion 14 may be made of different materials. Alternatively, the first channel portion 11 and the second functional portion 14 may be made of the same material, and different sheet resistances may be achieved by controlling the carrier concentration.

[0060] In some embodiments, the sheet resistance of the first channel portion 11 is greater than the sheet resistance of the first functional portion 13, and the sheet resistance of the first channel portion 11 is greater than the sheet resistance of the second functional portion 14. For example, the first channel portion 11, the first functional portion 13, and the second functional portion 14 can be made of different materials. Alternatively, the first channel portion 11, the first functional portion 13, and the second functional portion 14 can be made of the same material, and different sheet resistances can be achieved by controlling the carrier concentration.

[0061] Optionally, the carrier concentration of the first channel portion 11 is less than the carrier concentration of the first functional portion 13; and / or, the carrier concentration of the first channel portion 11 is less than the carrier concentration of the second functional portion 14.

[0062] In some embodiments, the material of the first channel portion 11 may be the same as the material of the first functional portion 13, and the carrier concentration of the first channel portion 11 is less than the carrier concentration of the first functional portion 13.

[0063] In some embodiments, the material of the first channel portion 11 may be the same as the material of the second functional portion 14, and the carrier concentration of the first channel portion 11 is less than the carrier concentration of the second functional portion 14.

[0064] In some embodiments, the materials of the first channel portion 11, the first functional portion 13, and the second functional portion 14 are all the same, the carrier concentration of the first channel portion 11 is less than the carrier concentration of the first functional portion 13, and the carrier concentration of the first channel portion 11 is less than the carrier concentration of the second functional portion 14.

[0065] Optionally, the first functional section 13 has a first concentration of donor impurity and a second concentration of acceptor impurity, and the first channel section 11 has a fifth concentration of donor impurity and a sixth concentration of acceptor impurity; and / or, the second functional section 14 has a third concentration of donor impurity and a fourth concentration of acceptor impurity, and the first channel section 11 has a fifth concentration of donor impurity and a sixth concentration of acceptor impurity.

[0066] In some embodiments, the first functional portion 13 is doped with a first concentration of donor impurity and a second concentration of acceptor impurity, and the first channel portion 11 is doped with a fifth concentration of donor impurity and a sixth concentration of acceptor impurity.

[0067] In some embodiments, the second functional portion 14 is doped with a third concentration of donor impurity and a fourth concentration of acceptor impurity, and the first channel portion 11 is doped with a fifth concentration of donor impurity and a sixth concentration of acceptor impurity.

[0068] In some embodiments, the first functional portion 13 is doped with a first concentration of donor impurity and a second concentration of acceptor impurity, the first channel portion 11 is doped with a fifth concentration of donor impurity and a sixth concentration of acceptor impurity, and the second functional portion 14 is doped with a third concentration of donor impurity and a fourth concentration of acceptor impurity.

[0069] Optionally, the absolute value of the third difference between the fifth concentration and the sixth concentration is less than the absolute value of the first difference between the first concentration and the second concentration; and / or, the absolute value of the third difference between the fifth concentration and the sixth concentration is less than the absolute value of the second difference between the second concentration and the fourth concentration.

[0070] In some embodiments, the absolute value of the third difference is less than the absolute value of the first difference.

[0071] In some embodiments, the absolute value of the third difference is less than the absolute value of the second difference.

[0072] In some embodiments, the absolute value of the third difference is less than the absolute value of the first difference, and the absolute value of the third difference is less than the absolute value of the second difference.

[0073] Optionally, the first difference and the third difference are both positive, or the first difference and the third difference are both negative; and / or, the second difference and the third difference are both positive, or the second difference and the third difference are both negative.

[0074] In some embodiments, the first difference and the third difference are both positive. That is to say, the first concentration is greater than the second concentration, and the fifth concentration is greater than the sixth concentration.

[0075] In some embodiments, the first difference and the third difference are both negative. That is to say, the first concentration is less than the second concentration, and the fifth concentration is less than the sixth concentration.

[0076] In some embodiments, the second and third differences are both positive. That is to say, the second concentration is greater than the fourth concentration, and the fifth concentration is greater than the sixth concentration.

[0077] In some embodiments, the second and third differences are both negative. That is to say, the second concentration is less than the fourth concentration, and the fifth concentration is less than the sixth concentration.

[0078] In some embodiments, the first and third differences are both positive, and the second and third differences are also both positive. That is to say, the first concentration is greater than the second concentration, the fifth concentration is greater than the sixth concentration, and the second concentration is greater than the fourth concentration.

[0079] In some embodiments, the first and third differences are both negative, and the second and third differences are also negative. That is to say, the first concentration is less than the second concentration, the fifth concentration is less than the sixth concentration, and the second concentration is less than the fourth concentration.

[0080] Optionally, the first concentration is equal to the fifth concentration, or the second concentration is equal to the sixth concentration; and / or, the third concentration is equal to the fifth concentration, or the fourth concentration is equal to the sixth concentration.

[0081] In some embodiments, the first concentration is equal to the fifth concentration.

[0082] In some embodiments, the second concentration is equal to the sixth concentration.

[0083] In some embodiments, the third concentration is equal to the fifth concentration.

[0084] In some embodiments, the fourth concentration is equal to the sixth concentration.

[0085] In some embodiments, the first concentration, the third concentration, and the fifth concentration are all equal.

[0086] In some embodiments, the second concentration, the fourth concentration, and the sixth concentration are all equal.

[0087] In some embodiments, the first concentration is equal to the fifth concentration, and the fourth concentration is equal to the sixth concentration.

[0088] In some embodiments, the second concentration is equal to the sixth concentration, and the third concentration is equal to the fifth concentration.

[0089] Optionally, such as Figure 1As shown, the thin-film transistor 1 further includes a second channel portion 15 stacked with the first channel portion 11. One end of the second channel portion 15 is in contact with the first functional portion 13, and the other end of the second channel portion 15 is in contact with the second functional portion 14. The carrier concentration of the second channel portion 15 is greater than that of the first channel portion 11.

[0090] like Figure 1 As shown, the first channel portion 11 and the second channel portion 15 are stacked, meaning that the second channel portion 15 is disposed on one side surface of the first channel portion 11. For example, the second channel portion 15 may be disposed on the upper surface of the first channel portion 11, or the second channel portion 15 may be disposed on the lower surface of the first channel portion 11.

[0091] like Figure 1 As shown, one end of the second channel portion 15 is in contact with the first functional portion 13, and the other end of the second channel portion 15 is in contact with the second functional portion 14. This means that one end of the second channel portion 15 is conductive to the first functional portion 13, allowing charge carriers to migrate between the first functional portion 13 and the second channel portion 15. The other end of the second channel portion 15 is conductive to the second functional portion 14, allowing charge carriers to migrate between the second functional portion 14 and the second channel portion 15.

[0092] In some embodiments, the sidewall of one end of the second channel portion 15 contacts the sidewall of the first functional portion 13. That is, the thickness of the first channel portion 11 is less than the thickness of the first functional portion 13, thereby exposing the sidewall of the first functional portion 13, and the exposed surface of the first functional portion 13 contacts the second channel portion 15.

[0093] The sidewall at one end of the second channel portion 15 contacts the sidewall of the second functional portion 14. That is to say, the thickness of the first channel portion 11 is less than the thickness of the second functional portion 14, thereby exposing the sidewall of the second functional portion 14, and the exposed surface of the second functional portion 14 contacts the second channel portion 15.

[0094] In some embodiments, one end of the second channel portion 15 overlaps with the first functional portion 13. That is, the side surface of the second channel portion 15 near the first functional portion 13 is in contact with the side surface of the first functional portion 13 near the second channel portion 15.

[0095] In some embodiments, the other end of the second channel portion 15 overlaps with the second functional portion 14. That is, the side surface of the second channel portion 15 near the second functional portion 14 is in contact with the side surface of the second functional portion 14 near the second channel portion 15.

[0096] It should be noted that other processes can also be used to achieve contact between one end of the second channel portion 15 and the first functional portion 13, and between the other end of the second channel portion 15 and the second functional portion 14. This application does not impose any limitations on this.

[0097] The carrier concentration in the second channel section 15 is greater than that in the first channel section 11. This configuration ensures that the channel current is sufficiently large to meet the high current requirements of the device.

[0098] In some embodiments, the second channel portion 15 is made of a different material than the first channel portion 11, thereby increasing the carrier concentration of the second channel portion 15 compared to the first channel portion 11. For example, the first channel portion 11 is made of polysilicon, and the second channel portion 15 is made of metal-oxide-semiconductor. The first channel portion 11 and the second channel portion 15 may also be made of other materials, which are not limited herein.

[0099] In some embodiments, the second channel portion 15 is made of the same material as the first channel portion 11. For example, both the first channel portion 11 and the second channel portion 15 are made of polycrystalline silicon. The grain size of the polycrystalline silicon in the second channel portion 15 is larger than that in the first channel portion 11. When the grain size of the polycrystalline silicon is larger, the grain boundary area is relatively smaller, and the scattering effect of the grain boundaries on the carriers moving in the polycrystalline silicon is weaker, allowing them to move more freely. This is beneficial for carrier transport, making the carrier concentration more effectively reflected to a certain extent. That is, under the same doping conditions, the carrier mobility of polycrystalline silicon with larger grain size is higher, which macroscopically manifests as carriers participating more easily in conduction, equivalent to a higher "effective utilization rate" of carrier concentration and a lower sheet resistance. In other words, the sheet resistance of the second channel portion 15 is less than that of the first channel portion 11.

[0100] In some embodiments, the second channel portion 15 is made of the same material as the first channel portion 11. For example, both the first channel portion 11 and the second channel portion 15 are made of polysilicon. The carrier concentration of the second channel portion 15 is greater than that of the first channel portion 11, thereby making the sheet resistance of the second channel portion 15 less than that of the first channel portion 11.

[0101] Optionally, such as Figure 1 As shown, the thin-film transistor 1 also includes a gate 20, which is disposed on the side of the second channel portion 15 away from the first channel portion 11. The gate 20 is disposed in the same layer as the source 30 and the drain 40.

[0102] Gate 20 can be a top gate or a bottom gate. In this application, gate 20 is described as a top gate, which should not be construed as a limitation of this application.

[0103] The gate 20 is disposed on the side of the second channel portion 15 away from the first channel portion 11. That is to say, relative to the first channel portion 11, the gate 20 is closer to the second channel portion 15. Through the above arrangement, the gate 20 can have a stronger control over the second channel portion 15, which is conducive to increasing the on-state current in the second channel portion 15 and realizing a high-current thin-film transistor 1.

[0104] It should be noted that, as Figure 1 As shown, the first channel portion 11 and the second channel portion 15 are stacked, allowing current to flow along the first channel portion 11 and / or the second channel portion 15. Compared to a thin-film transistor 1 with only one channel portion, this increases the on-state current of the thin-film transistor 1. Since the sheet resistance of the second channel portion 15 is less than that of the first channel portion 11, the current in the second channel portion 15 can be further increased, further increasing the on-state current of the thin-film transistor 1.

[0105] Optionally, the resistance of the first channel portion 11 is greater than the resistance of the second functional portion 14, the resistance of the second functional portion 14 is greater than the resistance of the first functional portion 13, the resistance of the first functional portion 13 is greater than the resistance of the first contact portion 12, and the resistance of the first contact portion 12 is equal to the resistance of the second contact portion 16.

[0106] In some embodiments, the sheet resistance of the first channel portion 11 is greater than the sheet resistance of the second functional portion 14, and the sheet resistance of the second functional portion 14 is greater than the sheet resistance of the first functional portion 13, and the sheet resistance of the first functional portion 13 is greater than the sheet resistance of the first contact portion 12. The resistance of the first contact portion 12 is equal to the resistance of the second contact portion 16.

[0107] In some embodiments, the sheet resistance of the first channel portion 11 is 10. 8 ~10 10 Ohms per square (Ω / sq), etc.

[0108] In some embodiments, the sheet resistance of the second functional unit 14 is 5*10. 4 ~5*10 6 Ohms per square (Ω / sq), etc.

[0109] In some embodiments, the sheet resistance of the first functional unit 13 is 10. 4 ~10 6 Ohms per square (Ω / sq), etc.

[0110] In some embodiments, the sheet resistance of the first contact portion 12 and the second contact portion 16 is 10 to 500 ohms per square (Ω / sq), etc.

[0111] like Figure 1 The diagram shown is a process flow chart of the fabrication of the thin-film transistor 1 of this application.

[0112] like Figures 2A to 2H and Figure 2A As shown, a substrate 55 is provided, and a first semiconductor layer 62 is formed on the substrate 55. The first semiconductor layer 62 is doped with donor impurities or acceptor impurities.

[0113] In some embodiments, the substrate 55 may be glass or the like.

[0114] In some embodiments, such as Figure 2B As shown, a light-shielding layer 51 can be formed on the substrate 55 before the first semiconductor layer 62 is formed. The light-shielding layer 51 can be formed by a patterning process. The light-shielding layer 51 is located directly below the channel region of the thin-film transistor 1 to shield the channel region of the thin-film transistor 1 from light and prevent the channel region from being degraded by light. The material of the light-shielding layer 51 can be a high-temperature resistant metal material such as Mo, Ti, or MoTi.

[0115] The patterning process includes steps such as coating photoresist, exposure and development, etching, and photoresist removal.

[0116] In some embodiments, a buffer layer 56 may also be formed on the substrate 55. The material of the buffer layer 56 may be any of SiOx, Al2O3 / SiNx / SiOx, SiOx / SiNx / SiOx, etc. Al2O3 / SiNx / SiOx refers to a stack of three layers: Al2O3, SiNx, and SiOx; SiOx / SiNx / SiOx refers to a stack of three layers: SiOx, SiNx, and SiOx. The meaning of the " / " between the various materials in the following text is similar.

[0117] In some embodiments, the material of the first semiconductor layer 62 may be polycrystalline silicon, which may be formed by crystallization of amorphous silicon.

[0118] In some embodiments, the first semiconductor layer 62 may be doped with donor impurities, such as phosphorus ions to form an N-type heavy doping. Alternatively, the first semiconductor layer 62 may be doped with acceptor impurities, such as boron ions to form a P-type heavy doping.

[0119] In some embodiments, the regions of the first semiconductor layer 62 are doped with the same type of ions and have the same ion concentration, thereby simplifying the fabrication process.

[0120] like Figure 2A As shown, the first semiconductor layer 62 is patterned to form a shape corresponding to the active portion 10.

[0121] like Figure 2BAs shown, an interlayer insulating layer 52 is formed on the active part 10, and a photoresist layer 61 is formed on the interlayer insulating layer 52. The interlayer insulating layer 52 and the photoresist layer 61 are patterned, and the first semiconductor layer 62 is doped using the photoresist layer 61 as a mask.

[0122] In some embodiments, the material of the interlayer insulating layer 52 can be any of SiOx, Al2O3 / SiNx / SiOx, SiOx / SiNx / SiOx, etc.

[0123] In some embodiments, the patterning process of the photoresist layer 61 can employ a half-grayscale photomask to form three different photoresist thicknesses, and use the photoresist as a mask to etch the interlayer insulating layer 52, exposing the area corresponding to the first channel portion 11.

[0124] It should be noted that, in one embodiment, such as Figure 2C As shown, during the etching of the interlayer insulating layer 52, the thickness of the first channel portion 11 is less than the thickness of the first functional portion 13, and the thickness of the first channel portion 11 is less than the thickness of the second functional portion 14, thereby exposing the sidewalls of the first functional portion 13 and the second functional portion 14. When the second semiconductor layer 63 is formed on the first channel portion 11, the exposed surfaces in the sidewalls of the first functional portion 13 and the exposed surfaces in the sidewalls of the second functional portion 14 will contact the second semiconductor layer 63.

[0125] Ion doping is performed on the first semiconductor layer 62 using a photoresist as a mask. The photoresist thickness corresponding to the first channel portion 11 is less than the photoresist thickness corresponding to the second functional portion 14, and the photoresist thickness corresponding to the second functional portion 14 is less than the photoresist thickness corresponding to the first functional portion 13. Under the same doping conditions, the smaller the photoresist thickness, the weaker its ability to block ions, allowing more ions to be doped into the first semiconductor layer 62 directly beneath the photoresist. This means that in this doping process, the ion concentration in the first channel portion 11 is greater than the ion concentration in the second functional portion 14, and the ion concentration in the second functional portion 14 is greater than the ion concentration in the first functional portion 13.

[0126] like Figure 2C As shown, in some embodiments, the photoresist thickness corresponding to the first channel portion 11 is zero. The photoresist thickness corresponding to the second functional portion 14 is less than the photoresist thickness corresponding to the first functional portion 13.

[0127] In some embodiments, in the first semiconductor layer 62 Figure 2C The concentration of doped ions is greater than or equal to Figure 2C The concentration of doped ions.

[0128] It should be noted that the ions used in this doping are similar to...Figure 2B The ions doped with it have opposite charges. That is to say, when... Figure 2B When the doped ions are donor impurities, then Figure 2B The first semiconductor layer 62 is doped with acceptor impurities. When Figure 2C When the doped ions are acceptor impurities, then Figure 2B The first semiconductor layer is doped with 62 donor impurities.

[0129] Due to the different photoresist thicknesses, the first channel portion 11, after doping, becomes the semiconductor with the highest resistance value in the first semiconductor layer 62, while the second functional portion 14 is a high-resistance region. The resistance relationship between each region is as follows: sheet resistance of the first channel portion 11 > sheet resistance of the second functional portion 14 > sheet resistance of the first functional portion 13 > sheet resistance of the first contact portion 12 = sheet resistance of the second contact portion 16. This configuration ensures that the sheet resistance of the second functional portion 14 is sufficiently high, thereby ensuring that the resistance of the drain region 40 is sufficiently high.

[0130] It should be noted that the first channel portion 11 can be a submicron channel. The first channel portion 11 can be formed by using an exposure machine with high-precision photoresist to form a photoresist with a length of about 1.2 micrometers corresponding to the first channel portion 11. Then, through a thermal process, the photoresist is reflowed by about 0.3 to 0.4 micrometers, so that the length of the first channel portion 11 is less than 1 micrometer, and finally a submicron channel is formed.

[0131] like Figure 2C As shown, the photoresist layer 61 is flocked to form nanopillars 611, and a second semiconductor layer 63 is formed on the photoresist layer 61 and the first channel portion 11.

[0132] In some embodiments, after the second semiconductor layer 63 is formed, one end of the second semiconductor layer 63 will overlap with the first functional part 13 and the other end will overlap with the second functional part 14, thereby making the area corresponding to the second channel part 15 connected with the first functional part 13 and the second functional part 14, thus forming a carrier flow channel.

[0133] In some embodiments, the material of the second semiconductor layer 63 may be polycrystalline silicon, which is formed by crystallization of amorphous silicon. The second semiconductor layer 63 may be doped with donor impurities or acceptor impurities.

[0134] It should be noted that after doping, the second semiconductor layer 63 and the first channel portion 11 have the same doping type, both being either P-type doped or both being N-type doped.

[0135] In some embodiments, by adjusting the crystallization conditions, such as crystallization temperature and laser energy, the grain size of the polycrystalline silicon in the second semiconductor layer 63 can be made larger than the grain size of the first semiconductor layer 62, thereby making the sheet resistance of the second semiconductor layer 63 smaller than the sheet resistance of the first semiconductor layer 62, and increasing the on-state current of the thin film transistor 1.

[0136] In some embodiments, the carrier concentration of the second semiconductor layer 63 is greater than that of the first channel portion 11, thereby making the sheet resistance of the second semiconductor layer 63 less than that of the first semiconductor layer 62, and increasing the on-state current of the thin film transistor 1.

[0137] It should be noted that the second semiconductor layer 63 can be formed by only one ion doping, and the carrier concentration of the second channel portion 15 is the seventh concentration. The first channel portion 11 is formed by two ion dopings with different electrical charges.

[0138] like Figure 2D As shown, the photoresist layer 61 and the second semiconductor layer 63 above the photoresist layer 61 are removed.

[0139] Because in Figure 2E In the process, nanopillars 611 are formed on the photoresist layer 61. The nanopillars 611 have an uneven surface, which increases the gap between the photoresist layer 61 and the second semiconductor layer 63. The etching solution can penetrate into the gap and peel off the photoresist layer 61 and the second semiconductor layer 63 above it together, retaining the pattern of the second channel portion 15 corresponding to the first channel portion 11.

[0140] In some embodiments, the process for removing the photoresist layer 61 can be a lift-off process. Using a lift-off process, the second channel portion 15 can be formed without a photomask, thereby simplifying the fabrication process of the thin-film transistor 1.

[0141] like Figure 2D As shown, a gate insulating layer 53 is formed on the second channel portion 15. The gate insulating layer 53 and the interlayer insulating layer 52 are patterned to form two vias. One via exposes the first contact portion 12, and the other via exposes the second contact portion 16.

[0142] In some embodiments, the material of the gate insulating layer 53 can be any of SiOx, Al2O3 / SiNx / SiOx, SiOx / SiNx / SiOx, etc.

[0143] like Figure 2F As shown, a source 30, a drain 40, and a gate 20 are formed on the gate insulating layer 53.

[0144] In some embodiments, the source 30, drain 40, and gate 20 are made of the same material, namely any one of Mo, Mo / Al, Mo / Cu, MoTi / Cu, MoTi / Cu / MoTi, Ti / Al / Ti, Ti / Cu / Ti, Mo / Cu / IZO, IZO / Cu / IZO, Mo / Cu / ITO, etc. By setting the source 30, drain 40, and gate in the same layer, the source 30, drain 40, and gate can be formed from the same metal layer through a patterning process, thereby saving photomask space.

[0145] like Figure 2G As shown, a passivation layer 54 is formed on the source 30, drain 40 and gate 20.

[0146] In some embodiments, the material of the passivation layer 54 can be any of SiOx, Al2O3 / SiNx / SiOx, SiOx / SiNx / SiOx, etc. The passivation layer 54 can protect the source 30, drain 40, and gate 20.

[0147] According to the second aspect of this application, such as Figure 2H As shown, a display panel 2 is provided, including the thin-film transistor 1 described above.

[0148] In some embodiments, the display panel 2 can be an LCD panel, an OLED panel, a Mini-LED panel, a Micro-LED panel, etc. The thin-film transistor 1 can be used as a driving transistor or a switching transistor in the display panel 2.

[0149] The display panel 2 includes a display area and a non-display area surrounding the display area. The display area may have multiple sub-pixels, including red, green, and blue sub-pixels, to achieve color display. Each sub-pixel may include a pixel driving circuit to control its light emission. The non-display area may have a gate 20 driving circuit, which provides driving signals to the sub-pixels.

[0150] In some embodiments, the thin-film transistor 1 can be applied in the driving circuit of the display panel 2, such as in a pixel driving circuit and / or a gate 20 driving circuit, as a driving transistor and / or a switching transistor.

[0151] In some embodiments, such as Figure 3 As shown, display panel 2 is an OLED panel. Display panel 2 includes multiple light-emitting units, each light-emitting unit corresponding to a sub-pixel. The light-emitting unit may include an anode 21, a light-emitting material layer 22, and a cathode 23 stacked together. The anode 21 provides holes, and the cathode 23 provides electrons. Holes and electrons recombine in the light-emitting material layer 22 to emit light.

[0152] The drain 40 of the thin-film transistor 1 can be electrically connected to the anode 21 to provide a driving voltage for the anode 21.

[0153] In some embodiments, such as Figure 3 As shown, the display panel 2 also includes an encapsulation layer 24. The encapsulation layer 24 is disposed on the side of the cathode 23 facing away from the substrate 55, and the encapsulation layer 24 can be formed by alternatingly stacked one or more organic layers 241 and one or more inorganic layers 242. For example, the organic layer 241 can be a single layer or multiple layers formed from any one of polyethylene terephthalate, polyimide, polycarbonate, epoxy resin, polyethylene, and polyacrylate. The inorganic layer 242 can be a single layer or multiple layers of metal oxides or metal nitrides, such as silicon nitride, aluminum oxide, silicon oxide, etc.

[0154] According to the third aspect of this application, such as Figure 3 As shown, a display terminal 3 is provided, including the display panel 2 described above.

[0155] In this embodiment, as Figure 4 Figure 4 As shown, the display terminal 3 includes a thin-film transistor 1 and a terminal body 4, which are combined into one unit.

[0156] In this embodiment, the display terminal 3 can be any product or component with display function, such as a mobile phone, tablet computer, television, monitor, laptop computer, digital photo frame, or navigator.

[0157] In the description of this application, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more features. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0158] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0159] The embodiments, implementation methods, and related technical features of this application can be combined and substituted for each other without conflict.

[0160] The above description is merely a preferred embodiment of this application and does not constitute any limitation on this application. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of this application without departing from the scope of the technical solution of this application shall still fall within the scope of the technical solution of this application.

Claims

1. A thin-film transistor, characterized in that, include: An active part includes a first channel portion, a first contact portion and a second contact portion disposed at both ends of the first channel portion, a first functional portion disposed between the first channel portion and the first contact portion, and a second functional portion disposed between the first channel portion and the second contact portion. The source and drain are connected, with the source connected to the first contact portion and the drain connected to the second contact portion. Wherein, the resistance of the first functional unit is less than the resistance of the second functional unit.

2. The thin-film transistor according to claim 1, characterized in that, The carrier concentration of the first functional unit is greater than that of the second functional unit.

3. The thin-film transistor according to claim 2, characterized in that, The first functional unit has a first concentration of donor impurity and a second concentration of acceptor impurity, and the second functional unit has a third concentration of donor impurity and a fourth concentration of acceptor impurity.

4. The thin-film transistor according to claim 3, characterized in that, The absolute value of the first difference between the first concentration and the second concentration is greater than the absolute value of the second difference between the third concentration and the fourth concentration.

5. The thin-film transistor according to claim 4, characterized in that, Both the first difference and the second difference are positive; or both the first difference and the second difference are negative.

6. The thin-film transistor according to claim 4, characterized in that, The first concentration is equal to the third concentration, or the second concentration is equal to the fourth concentration.

7. The thin-film transistor according to any one of claims 1 to 6, characterized in that, The active portion further includes a second channel portion stacked with the first channel portion, one end of the second channel portion being in contact with the first functional portion, and the other end of the second channel portion being in contact with the second functional portion. The carrier concentration in the second channel is greater than that in the first channel.

8. The thin-film transistor according to claim 7, characterized in that, The thin-film transistor further includes a gate, which is disposed on the side of the second channel portion away from the first channel portion, and the gate is disposed on the same layer as the source and the drain.

9. The thin-film transistor according to claim 1, characterized in that, The resistance of the first channel is greater than the resistance of the second functional part, the resistance of the first functional part is greater than the resistance of the first contact part, and the resistance of the first contact part is equal to the resistance of the second contact part.

10. A display panel, characterized in that, Including the thin-film transistor as described in any one of claims 1 to 9.

11. A display terminal, characterized in that, Includes the display panel as described in claim 10.

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