Thin film transistor substrate, display apparatus including the same, and method of manufacturing the same

Abstract

This application relates to thin-film transistor substrates, display devices including the same, and methods for manufacturing the same, wherein the method for manufacturing the thin-film transistor substrate includes: removing an oxide film on the surface of an amorphous silicon layer by performing surface cleaning; and forming an active layer by performing a heat treatment on the amorphous silicon layer, wherein the amorphous silicon layer is transformed into crystalline silicon by the heat treatment.

Description

[0001] This application claims priority to and all benefits derived therefrom of Korean Patent Application No. 10-2019-0084545, filed on July 12, 2019, the contents of which are incorporated herein by reference in their entirety. Technical Field

[0002] One or more embodiments relate to thin-film transistor substrates used in display devices and the like, and more specifically, to thin-film transistor substrates including active layers with improved structures, display devices including thin-film transistor substrates, and methods for manufacturing thin-film transistor substrates and display devices. Background Technology

[0003] Generally, display devices, such as organic light-emitting display devices, include thin-film transistors for driving each pixel, and the thin-film transistors include an active layer. The active layer is typically formed on a substrate in an amorphous state and then crystallized through appropriate heat treatment. Summary of the Invention

[0004] In the crystallization process used for active layers, protrusions that extend above the surface can be formed at the boundaries between crystalline grains. That is, during heat treatment, as amorphous silicon transforms into crystalline silicon, the crystalline grains collide and form boundaries as they grow, and these protrusions can form on the surface at the boundaries of the colliding grains.

[0005] However, when the protrusion becomes too large, the electric field concentrates at its tip, thus increasing deviations in the device's electrical characteristics and causing unintended instability. Furthermore, the protrusion can be perceived by the user as a pattern, such as a moiré pattern, appearing as unwanted spots on the screen. Consequently, this can reduce product reliability.

[0006] Specifically, the oxide film on the surface of the amorphous active layer prior to crystallization has been noted as a major factor in increasing the size of the protrusions.

[0007] Accordingly, one or more embodiments include a thin-film transistor substrate improved to address excessive concentration of electric field on protrusions and screen quality defects due to the visibility of speckle patterns by reducing the size of protrusions formed at the grain boundaries of the active layer; a display device including a thin-film transistor substrate; and a method of manufacturing the thin-film transistor substrate and the display device.

[0008] According to an embodiment, a method for manufacturing a thin-film transistor substrate includes: providing an amorphous silicon layer over a substrate; removing an oxide film on the surface of the amorphous silicon layer by performing surface cleaning; and forming an active layer by performing a heat treatment on the amorphous silicon layer, wherein the amorphous silicon layer is transformed into a crystalline silicon layer by the heat treatment.

[0009] In one embodiment, removing the oxide film on the surface of the amorphous silicon layer by performing surface cleaning may include removing the oxide film by spraying a hydrogen fluoride solution onto the surface of the amorphous silicon layer.

[0010] In this embodiment, the hydrogen fluoride solution may include about 0.5 volume percentages (vol%) of hydrogen fluoride.

[0011] In one embodiment, removing the oxide film on the surface of the amorphous silicon layer by performing surface cleaning may further include: performing a first rinsing cleaning, including supplying hydrogen water to the surface of the amorphous silicon layer in a free-fall manner.

[0012] In one embodiment, removing the oxide film on the surface of the amorphous silicon layer by performing surface cleaning may further include performing a second rinsing cleaning, which includes supplying hydrogen water to the surface of the amorphous silicon layer in a free-fall manner while applying vibration to the hydrogen water using mega-frequency ultrasound.

[0013] In one embodiment, forming an active layer may include: radiating a laser beam onto an amorphous silicon layer disposed above a substrate, wherein the laser beam may have a long side and a short side in a first direction and a second direction perpendicular to each other, respectively; and moving the substrate by a predetermined pitch in a second direction parallel to the short side.

[0014] In one implementation, the laser beam can be repeatedly turned on and off whenever the substrate moves a predetermined pitch, wherein the predetermined pitch can be set to allow the laser beam to be turned on at least 7 times in a cell region of the amorphous silicon layer.

[0015] In one embodiment, the method may further include providing a buffer layer between a substrate and an amorphous silicon layer, wherein the thickness of the amorphous silicon layer may be approximately 370 angstroms. to approximately Within the range, and the buffer layer may include a thickness of approximately to approximately SiO x .

[0016] According to an embodiment, a thin-film transistor substrate includes: a substrate, an active layer above the substrate, a gate electrode facing the active layer, a source electrode connected to the active layer, and a drain electrode connected to the active layer, wherein the surface of the active layer includes protrusions, and the height of the protrusions is about 3 nanometers (nm) or less.

[0017] In one embodiment, the thin-film transistor substrate may further include a buffer layer between the substrate and the active layer, wherein the thickness of the amorphous silicon layer may be approximately [missing information]. to approximately The buffer layer may include a thickness of approximately to approximately SiO x .

[0018] According to an embodiment, a method for manufacturing a display device includes: providing a thin-film transistor over a substrate, and providing an organic light-emitting device connected to the thin-film transistor, wherein providing the thin-film transistor includes: providing an amorphous silicon layer over the substrate; removing an oxide film on the surface of the amorphous silicon layer by performing surface cleaning; and forming an active layer by performing a heat treatment on the amorphous silicon layer, wherein the amorphous silicon layer becomes a crystalline silicon layer by the heat treatment.

[0019] In one embodiment, removing the oxide film on the surface of the amorphous silicon layer by performing surface cleaning may include spraying a hydrogen fluoride solution onto the surface of the amorphous silicon layer.

[0020] In this embodiment, the hydrogen fluoride solution may include about 0.5 vol% hydrogen fluoride.

[0021] In one embodiment, removing the oxide film on the surface of the amorphous silicon layer by performing surface cleaning may further include: performing a first rinsing cleaning, including supplying hydrogen water to the surface of the amorphous silicon layer in a free-fall manner.

[0022] In one embodiment, removing the oxide film on the surface of the amorphous silicon layer by performing surface cleaning may further include performing a second rinsing cleaning, which includes supplying hydrogen water to the surface of the amorphous silicon layer in a free-fall manner while applying vibration to the hydrogen water using mega-frequency ultrasound.

[0023] In one embodiment, forming an active layer may include: radiating a laser beam onto an amorphous silicon layer disposed above a substrate, wherein the laser beam may have a long side and a short side in a first direction and a second direction perpendicular to each other, respectively; and moving the substrate by a predetermined pitch in a second direction parallel to the short side.

[0024] In one implementation, the laser beam can be repeatedly turned on and off whenever the substrate moves a predetermined pitch, wherein the predetermined pitch can be set to allow the laser beam to be turned on at least 7 times in a cell region of the amorphous silicon layer.

[0025] In one embodiment, the method may further include providing a buffer layer between the substrate and the amorphous silicon layer, wherein the thickness of the amorphous silicon layer may be approximately [missing information]. to approximately Within the range, the buffer layer may include a thickness of to approximately SiO x .

[0026] According to an embodiment, the display device includes: a thin-film transistor above a substrate and an organic light-emitting device connected to the thin-film transistor, wherein the thin-film transistor includes: an active layer above the substrate, a gate electrode facing the active layer, a source electrode connected to the active layer, and a drain electrode connected to the active layer, wherein the surface of the active layer includes protrusions, and the height of the protrusions is about 3 nm or less.

[0027] In one embodiment, the display device may further include a buffer layer between the substrate and the active layer, wherein the thickness of the amorphous silicon layer may be [missing information]. to approximately Within the range, and the buffer layer may include a thickness of approximately to approximately SiO x . Attached Figure Description

[0028] The above and other features of the embodiments of this disclosure will become more apparent from the following description taken in conjunction with the accompanying drawings, wherein:

[0029] Figure 1 This is a plan view of a display device including a thin-film transistor according to an embodiment;

[0030] Figure 2 for Figure 1 The equivalent circuit diagram of the pixels of the display device shown in the image;

[0031] Figure 3 for Figure 1 The cross-sectional view of the display device shown in the image;

[0032] Figures 4A to 4H To display Figure 3 A cross-sectional view of an embodiment of the manufacturing process of a thin-film transistor substrate shown in the figure;

[0033] Figure 5A and Figure 5B To show a cross-sectional view of a conventional method used as a comparative example, in which the amorphous silicon layer crystallizes without removing the oxide film; and

[0034] Figure 6 To describe in a planar direction Figure 4F The diagram shows a plan view of the laser beam irradiation process. Detailed Implementation

[0035] The invention will now be described more fully below with reference to the accompanying drawings, in which various embodiments are shown. However, the invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. The same reference numerals refer to the same elements throughout.

[0036] It will be understood that although the terms “first,” “second,” “third,” etc., may be used herein to describe various elements, components, regions, layers, and / or sections, these elements, components, regions, layers, and / or sections should not be limited by these terms. These terms are used only to distinguish one element, component, region, layer, or section from another. Therefore, without departing from the teachings of this document, “first element,” “first component,” “first region,” “first layer,” or “first section” discussed below may be referred to as a second element, second component, second region, second layer, or second section.

[0037] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used herein, the singular forms “a,” “an,” and “described” are intended to include the plural forms, including “at least one,” unless the content clearly indicates otherwise. “Or” means “and / or.” As used herein, the term “and / or” includes any and all combinations of one or more of the associated enumerated items. It will be further understood that the terms “comprises” and / or “comprising” or “includes” and / or “including”, when used in this specification, specify the presence of the described features, areas, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, areas, integers, steps, operations, elements, components, and / or groups thereof.

[0038] For ease of description, spatial relative terms such as “below,” “under,” “down,” “above,” “up,” etc., may be used herein to describe the relationship between one element or feature shown in the figures and another element (or feature) or feature (or feature). It will be understood that spatial relative terms are intended to cover different orientations of the device in use or operation, other than those depicted in the figures. For example, if the device in the figures is flipped, the element described as being “below” or “under” other elements or features would then be oriented “above” other elements or features. Thus, the exemplary term “below” can cover both above and below orientations. The device may be oriented in other ways (rotated 90 degrees or in other orientations) and the spatial relative descriptors used herein shall be interpreted accordingly.

[0039] It will be further understood that when a layer, region, or component is referred to as being "on" another layer, region, or component, it can be directly or indirectly on that other layer, region, or component. That is, for example, intermediate layers, regions, or components may exist.

[0040] As used herein, “about” or “approximately” includes, taking into account the measurements under discussion and the errors associated with a particular number of measurements (i.e., limitations of the measurement system), the stated values ​​and the average values ​​within an acceptable range of deviation from the particular values ​​as determined by one of ordinary skill in the art.

[0041] Unless otherwise specified, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. It will be further understood that terms, such as those defined in common dictionaries, should be interpreted as having the same meaning as they have in the relevant field and in the context of this disclosure, and will not be interpreted in an idealized or overly formal sense unless expressly so specified herein.

[0042] For ease of explanation, the dimensions of the components in the figures may be enlarged or reduced. In other words, since the dimensions and thicknesses of the components in the figures are arbitrarily shown for ease of explanation, this description is not limited thereto.

[0043] This document describes exemplary embodiments with reference to schematic cross-sectional views as preferred embodiments. Thus, variations in the shapes of the figures should be expected due to factors such as manufacturing techniques and / or tolerances. Therefore, the embodiments described herein should not be construed as limited to the specific shapes of the areas shown herein, but should include deviations in shape due to factors such as manufacturing. For example, areas shown or described as flat may generally have rough and / or non-linear characteristics. Furthermore, sharp corners shown may be rounded. Therefore, the areas shown in the figures are schematic in nature, and their shapes are not intended to represent the precise shapes of the areas and are not intended to limit the scope of the claims of the invention.

[0044] When different implementation methods are possible, a certain process sequence may be performed differently from the order in which they are described. For example, two consecutively described processes may be performed substantially simultaneously or in the reverse order of their description.

[0045] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0046] Figure 1 This is a schematic plan view of the display device 100 according to an embodiment, and Figure 2 for Figure 1 The equivalent circuit diagram of pixel P of display device 100 shown in the figure.

[0047] refer to Figure 1 An embodiment of the display device 100 may include a display area DA and a peripheral area PA above the substrate 130.

[0048] On substrate 130, a plurality of pixels P are arranged in display area DA. In an exemplary embodiment, such as Figure 2 As shown, each pixel P may include a pixel circuit PC and an organic light-emitting device (OLED), the OLED being a display element connected to the pixel circuit PC. The pixel circuit PC may include a first thin-film transistor T1, a second thin-film transistor T2, and a storage capacitor Cst. Each pixel P may emit, for example, red, green, or blue light through the OLED, or may emit red, green, blue, or white light.

[0049] A second thin-film transistor T2, acting as a switching thin-film transistor, can be connected to the scan line SL and the data line DL, and based on the switching voltage input from the scan line SL, can provide the data voltage input from the data line DL to the first thin-film transistor T1. In this embodiment, the scan line SL can extend in a first direction x, and the data line DL can extend in a second direction y intersecting the first direction x. A third direction z( Figure 3 (As shown in the image) can be a direction perpendicular to the first direction x and the second direction y, or the thickness direction of the substrate 130. The storage capacitor Cst can be connected to the second thin-film transistor T2 and the drive voltage line PL, and can store a voltage corresponding to the difference between the voltage received from the second thin-film transistor T2 and the first power supply voltage ELVDD supplied to the drive voltage line PL.

[0050] A first thin-film transistor T1, acting as a driving thin-film transistor, can be connected to a driving voltage line PL and a storage capacitor Cst. In response to the voltage value stored in the storage capacitor Cst, the driving current flowing from the driving voltage line PL to the organic light-emitting device (OLED) can be controlled. The OLED can emit light with a brightness corresponding to the driving current. The electrodes (e.g., cathodes) of the OLED can be supplied with a second power supply voltage ELVSS.

[0051] In the implementation method, such as Figure 2 As shown, the pixel circuit PC may include two thin-film transistors and a single storage capacitor, but the implementation is not limited to this. Depending on the design of the pixel circuit PC, the number of thin-film transistors and the number of storage capacitors in each pixel circuit PC can be modified differently. For example, in one embodiment, in addition to the two thin-film transistors described above, the pixel circuit PC may further include one or more thin-film transistors.

[0052] Refer back Figure 1 Scan driver 180 for providing scan signals to each pixel P, data driver 190 for providing data signals to each pixel P, etc., can be arranged in the peripheral area PA on the substrate 130. Figure 1An embodiment in which the data driver 190 is adjacent to the lateral edge of the substrate 130 is shown. In an alternative embodiment, the data driver 190 may be arranged on a flexible printed circuit board (“FPCB”) electrically connected to pads arranged on the edge of the substrate 130.

[0053] Reference Figure 3 The cross-sectional structure of an embodiment of a display device 100 including a thin-film transistor 110 is described.

[0054] Figure 3 for Figure 1 The cross-sectional view of the display device 100 shown in the image.

[0055] The above is for reference only. Figure 2 The first thin-film transistor T1 and the second thin-film transistor T2 described can both have corresponding Figure 3 The structure of the thin-film transistor 110 shown is illustrated, but here the thin-film transistor 110 can be understood as an implementation of the first thin-film transistor T1, which is the driving thin-film transistor of the organic light-emitting device OLED.

[0056] In the implementation method, such as Figure 3 As shown in the image, the display device 100 includes a thin-film transistor 110 and an organic light-emitting device 120.

[0057] An organic light-emitting device 120 driven by a thin-film transistor 110 to display an image by emitting light includes pixel electrodes 121 and a counter electrode 123 opposite to each other, and an emitting layer 122 between the pixel electrodes 121 and the counter electrode 123.

[0058] A predetermined voltage is continuously applied to the opposing electrode 123, and the voltage is selectively applied via the thin-film transistor 110 to the pixel electrode 121 connected to the thin-film transistor 110. Accordingly, when an appropriate voltage difference is formed between the two electrodes (i.e., the pixel electrode 121 and the opposing electrode 123) based on the selective voltage applied by the thin-film transistor 110, the emitting layer 122 between the pixel electrode 121 and the opposing electrode 123 displays an image by emitting light.

[0059] In one embodiment, the thin-film transistor 110 has a structure in which an active layer 116, a gate electrode 117, a source electrode 118, and a drain electrode 119 are sequentially stacked on top of a substrate 130, one on top of the other. Accordingly, when an electrical signal is applied to the gate electrode 117, current is allowed to be applied through the active layer 116 from the source electrode 118 to the drain electrode 119, and thus a voltage is applied to the pixel electrode 121 connected to the drain electrode 119, which causes the emission of the aforementioned emitter layer 122. The structure including the thin-film transistor 110 and the substrate 130 may be referred to as a thin-film transistor substrate. In addition, the thin-film transistor substrate may further include a buffer layer between the substrate 130 and the active layer 116.

[0060] exist Figure 3 In the figure, reference numeral 111 indicates a buffer layer between substrate 130 and active layer 116, and reference numerals 112, 113, 114 and 115 indicate a gate insulating layer, an interlayer insulating layer, a passivation film and a pixel defining film, respectively.

[0061] In one embodiment, a hole injection layer (“HIL”), a hole transport layer (“HTL”), an electron transport layer (“ETL”), an electron injection layer (“EIL”), etc., may be further stacked adjacent to the emitter layer 122 in the organic light-emitting device 120. In another embodiment, the emitter layer 122 may be separate for each pixel, allowing pixels emitting red, green, and blue light to collectively constitute a unit pixel. Alternatively, the emitter layer 122 may be provided for the entire pixel area regardless of the pixel's location. In this embodiment, layers comprising luminescent materials for emitting, for example, red, green, and blue light may be stacked vertically in the emitter layer 122, or layers of luminescent materials for emitting, for example, red, green, and blue light may be mixed. Any combination of various other colors capable of emitting white light may be used. In another embodiment, a color conversion layer or color filter may be further included for converting the emitted white light into a certain color. In another embodiment, a thin-film encapsulation layer (not shown) comprising alternately stacked organic and inorganic films may be present on the opposing electrode 123.

[0062] In this embodiment, when forming the active layer 116, the following process is performed: an amorphous silicon layer is formed on a buffer layer 111 disposed on a substrate 130, and then the amorphous silicon layer is transformed into a crystalline silicon layer by heat treatment to crystallize it. During this heat treatment, the grains collide with each other while growing, and thus, protrusions 1 (see reference) can be formed at their boundaries. Figure 4F)。When the protrusion 1 grows too tall, the electric field concentrates on it, and thus, as described above, the deviation of the electrical characteristics of the device can be increased, resulting in undesired instability. Moreover, the protrusion 1 can be perceived by the user as a pattern, such as a moiré pattern, as if there are undesired spots on the screen. Accordingly, in an embodiment of the present invention, the following manufacturing process can be performed to control the height of the protrusion 1 of the active layer 116 (refer to Figure 4F ) to an appropriate height to effectively prevent the above problems.

[0063] Figures 4A to 4H An embodiment of an improved manufacturing process is shown to control the height of the protrusion 1 of the active layer 116 to be equal to or less than the appropriate height as described above.

[0064] In an embodiment, as Figure 4A shown, a buffer layer 111 is provided or formed on the substrate 130. In this embodiment, the buffer layer 111 includes SiO x and has a thickness in the range of about 4000 angstroms to about , where "x" can be greater than 0 and less than or equal to 2 (i.e., 0 < x ≤ 2). Generally, SiN x is used to form the buffer layer 111, but SiN x contains a lot of hydrogen, and accordingly, during the following crystallization process, a large amount of hydrogen can penetrate into the active layer 116, resulting in problems with the characteristics of the active layer 116. Accordingly, in an embodiment, SiO with a low hydrogen content is used x , and the buffer layer 111 is formed with a small thickness in the range of about to about .

[0065] In an embodiment, as Figure 4B shown, an amorphous silicon layer 116(A) that will be formed into the active layer 116 is provided or formed on the buffer layer 111, and the amorphous silicon layer 116(A) is also thin enough to have a thickness in the range of about to about . In an embodiment, when the amorphous silicon layer 116(A) is thick, for example, thicker than the thickness in the above range, the protrusion 1 can become larger later, and thus, the amorphous silicon layer 116(A) is formed with a small thickness substantially.

[0066] In this embodiment, as Figure 4BAs shown, an oxide film 116-1 is naturally formed on the amorphous silicon layer 116(A). Accordingly, the oxide film 116-1 is removed before crystallization. If the oxide film 116-1 is removed by conventional water cleaning or ozone (O3) cleaning, the oxide film 116-1 may not be completely removed, and its residue may be left everywhere, causing the residue of the oxide film 116-1 to cause the protrusion 1 of the active layer 116 to rise after crystallization. The reason for this will be described later.

[0067] Accordingly, in the implementation, such as Figure 4C The study shows that spraying a hydrogen fluoride solution containing approximately 0.5 volume percentage (vol%) of hydrogen fluoride (HF) onto the oxide film 116-1 for approximately 60 seconds to approximately 120 seconds effectively and completely removes the oxide film 116-1, and thus removes the oxide film 116-1 through a chemical reaction. When the hydrogen fluoride solution is sprayed as described above, the oxide film 116-1 can be effectively and completely removed without leaving any residue.

[0068] In the implementation method, such as Figure 4D The diagram shows that a first rinsing cleaning is performed on the surface of the amorphous silicon layer 116(A) after the oxide film 116-1 has been removed, using hydrogen-water DIW containing approximately one part per million (ppm) of hydrogen. In this embodiment, the hydrogen-water DIW is not sprayed but rather dripped in a free-falling manner to flow above the surface of the amorphous silicon layer 116(A). The hydrogen-water DIW is a liquid containing approximately 1 ppm of hydrogen and free of oxygen, and accordingly, although cleaning is performed using hydrogen-water DIW, an oxide film does not re-form on the surface of the amorphous silicon layer 116(A). However, when hydrogen-water DIW is sprayed, the surface area of ​​the liquid particles dispersed in the droplets increases dramatically, and therefore, the opportunity for oxygen to mix with it increases. Consequently, a second oxide film can form. Accordingly, in this embodiment, the surface of the amorphous silicon layer 116(A) is rinsed and cleaned by supplying hydrogen-water DIW in a free-falling manner instead of spraying hydrogen-water DIW.

[0069] In the implementation method, such as Figure 4E The diagram shows a second rinsing process. In this embodiment, the second rinsing is essentially the same as the first rinsing, which involves supplying a hydrogen-water DIW containing 1 ppm of hydrogen in a free-fall manner, except that the hydrogen-water DIW is supplied by adding vibrations to it using mega-frequency ultrasound. In this embodiment, the rinsing effect is further enhanced by the vibration of the liquid particles in the hydrogen-water DIW.

[0070] When an amorphous silicon layer 116(A) is prepared by the above process, resulting in the complete removal of the oxide film 116-1 without leaving any residue, as follows: Figure 4FThe diagram shows that a heat treatment process is performed to transform the amorphous silicon layer 116(A) into a crystalline silicon layer 116(P) by heating it with a radiating laser beam at a crystallization temperature or higher. The laser beam can be, for example, an excimer laser beam.

[0071] In this embodiment, as described above, protrusions 1 are formed as the grains grow through a melting and solidification process and collide at the grain boundaries. In this embodiment, because the residue of the oxide film 116-1 on the surface of the amorphous silicon layer 116(A) has been effectively and completely removed, and therefore heat is uniformly transferred throughout the entire region, the height h1 of the protrusion 1 is effectively maintained at about 3 nanometers (nm) or less. Hereinafter, the height h1 of the protrusion 1 is defined as the distance between the highest and lowest points of the upper surface of the crystalline silicon layer 116(P).

[0072] The embodiments of the present invention will be described below with reference to a comparative example using conventional heat treatment (in which a residue of oxide film 116-1 was left).

[0073] Figure 5A and Figure 5B To show a cross-sectional view of a conventional method as a comparative example, in which the amorphous silicon layer 116(A) is crystallized without removing the oxide film 116-1.

[0074] like Figure 5A As shown, when no removal operation with hydrogen fluoride solution is performed, and therefore, residue of oxide film 116-1 is left all over the surface of the amorphous silicon layer 116(A), local deviations occur solely due to heat transfer to the amorphous silicon layer 116(A) during laser beam radiation, and also solely due to heat dissipation during curing. That is, because the heat flow is uneven in areas shielded by the residue of oxide film 116-1, and relatively smooth in areas not shielded by the residue of oxide film 116-1, crystallization occurs more rapidly in areas where the heat flow is smooth, and therefore, the height h2 of the protrusion 1 becomes relatively much larger. In this case, when the residue of oxide film 116-1 is left, the height h2 of the protrusion 1 can be in the range of about 14 nm to about 16 nm. As a result, the characteristics of the active layer 116 used for thin-film transistors may later become problematic, and furthermore, the protrusion 1 can be large enough to be perceived as a spot by the user, which can reduce product quality.

[0075] In an embodiment of the invention, as described above, a crystallization heat treatment process is performed after sufficient removal of the oxide film 116-1 with a hydrogen fluoride solution, so that the height h1 of the protrusion 1 can be controlled to about 3 nm or less, and thus, product quality can be improved.

[0076] The following will refer to Figure 6 Describe in detail the radiation process of the laser beam.

[0077] After completing the above-mentioned crystallization heat treatment process, such as Figure 4G As shown, the crystalline silicon layer 116(P) is patterned to the size of the active layer 116 with thin-film transistors 110.

[0078] In the implementation method, such as Figure 4H As shown, the gate electrode 117 is formed facing the active layer 116, wherein the gate insulating layer 112 is between the gate electrode 117 and the active layer 116, and provides or forms an interlayer insulating layer 113, a source electrode 118 and a drain electrode 119.

[0079] Therefore, a thin-film transistor 110 with improved characteristics and without undesirable factors (such as electric field concentration in a certain area or visible spot patterns) is formed, and when the organic light-emitting device 120 is subsequently formed, a [missing information - likely a specific technology or process] is manufactured. Figure 3 The display device 100 shown in the middle.

[0080] According to experiments, compared with thin-film transistors manufactured by conventional methods, the spot pattern is reduced by about 20%, making the spot pattern virtually invisible to the naked eye. Furthermore, the deviation of the electrical characteristics of the thin-film transistor regions is improved by about 20% to about 45%, becoming highly uniform. Accordingly, when the aforementioned thin-film transistor 110 and display device 100 are implemented, their quality can be effectively and consistently obtained.

[0081] When a laser beam is radiated to crystallize the amorphous silicon layer 116(A), it can be used Figure 6 The radiation method shown in the image.

[0082] Multiple cells for crystallization are arranged in a row above substrate 130 in the first direction x and the second direction y, and each cell can be understood as a region corresponding to a unit of the amorphous silicon layer 116(A) for crystallization in the display area DA.

[0083] The laser beam Lb is directed to have the following properties: Figure 6 The long side in the second direction y and in Figure 6 The laser beam Lb radiates onto the unit cells disposed above the substrate 130 in a rectangular form along the short side in the first direction x, and radiates over the entire area of ​​each unit cell as the substrate 130 moves a predetermined pitch in the first direction x. The short side width W1 of the laser beam Lb is approximately 480 micrometers (μm), and the laser beam Lb radiates with an energy of approximately 440 millijoules (mJ) to approximately 480 mJ. The laser beam is not kept in an on state, but is repeatedly turned on / off whenever the substrate 130 moves a certain pitch.

[0084] In one embodiment, the moving direction (x) of the substrate 130 and the long side direction (y) of the laser beam Lb are perpendicular to each other. In this embodiment, laser irradiation can be performed such that the moving direction (x) of the substrate 130 and the long side direction (y) of the laser beam Lb are perpendicular to each other. In this embodiment of the invention, because the height of the protrusion 1 is about 3 nm or less, the moving direction (x) of the substrate 130 and the long side direction (y) of the laser beam Lb are allowed to be perpendicular to each other during the laser beam irradiation process.

[0085] In the relevant field, when the protrusion 1 is high enough to reach about 15nm, the height of the protrusion 1 itself is sufficient to allow the user to perceive the protrusion 1 as a spot, and when the effect caused by the energy deviation due to the on / off of the laser beam Lb is added, the spot can appear larger.

[0086] That is, when the laser beam Lb is turned on, the central region receives relatively more energy than the edge region, and when the laser beam Lb is turned on again after a certain pitch, the central region again receives relatively more energy than the edge region. Therefore, this deviation can cause a difference in the degree of crystallization between the central and edge regions, resulting in a striped pattern that repeats in the first direction x and extends in the second direction y. The striped pattern itself is not clearly visible to the user; however, when the striped pattern is combined with a spot pattern caused by the significant height of the protrusion 1, the striped pattern can make the spot pattern more clearly visible. Accordingly, in conventional methods, the long side of the laser beam Lb and the direction of movement of the substrate 130 are allowed to form an 89-degree angle, which is tilted by 1 degree relative to 90 degrees, to crystallize and solve the above problem. Because the protrusion 1 is formed in a unit cell arranged in directions x and y, the striped pattern caused by the radiation deviation of the laser beam Lb is slightly tilted and not aligned with directions x and y. Therefore, the spot pattern caused by the significant height of protrusion 1 and the stripe pattern caused by the radiation deviation of the laser beam Lb may not be precisely aligned.

[0087] However, when the laser beam Lb is tilted to prevent the long side of the laser beam Lb from being perpendicular to the direction of movement of the substrate 130, the laser beam Lb moves diagonally across the substrate 130, and therefore, dead space is added in the substrate 130 that does not contact the laser beam Lb. That is, the area of ​​the substrate 130 may not be used effectively.

[0088] In embodiments of the present invention, as described above, the height of the protrusion 1 can be controlled to about 3 nm or less, and therefore, although combined with a striped pattern due to energy deviation of the laser beam Lb, the protrusion 1 can be invisible to the user. Accordingly, as Figure 6As shown, laser radiation can be performed so that the moving direction (x) of the substrate 130 and the long side direction (y) of the laser beam Lb are perpendicular to each other.

[0089] This also reduces the stripe pattern caused by energy deviation of the laser beam Lb, and for this purpose, the movement pitch can be set to activate the laser beam Lb at least 7 times per unit cell. The activation of the laser beam Lb is generally referred to as firing, and the movement pitch of the substrate 130 is set to perform 7 or more close firings per unit cell. In one embodiment, for example, when the movement pitch is set in the range of about 1 μm to about 68 μm, using a laser beam Lb with a short side of about 480 μm, at least 7 firings can generally be performed per unit cell, and correspondingly, the stripe pattern caused by energy deviation of the laser beam Lb can also be reduced.

[0090] Accordingly, when using a thin-film transistor substrate, a display device including a thin-film transistor substrate, and an embodiment of a method for manufacturing a thin-film transistor substrate and a display device, by reducing the size of the protrusions formed at the grain boundaries of the active layer, the excessive concentration of the electric field on the protrusions and the screen quality defects caused by the visibility of the spot pattern can be solved, and thus, the quality and reliability of the product can be obtained.

[0091] It should be understood that the embodiments described herein are to be considered in a descriptive sense only and not for limiting purposes. The description of features or aspects in each embodiment should generally be considered as applicable to other similar features or aspects in other embodiments. While one or more embodiments have been described with reference to the figures, those skilled in the art will understand that various changes in form and detail may be made therein without departing from the spirit and scope defined by the following claims.

Claims

1. A method for manufacturing a thin-film transistor substrate, the method comprising: An amorphous silicon layer is provided above the substrate; An oxide film is formed on the surface of the amorphous silicon layer without using an oxidation solution; The oxide film on the surface of the amorphous silicon layer is removed by surface cleaning without the use of an oxidation solution; and An active layer is formed by heat treatment on the amorphous silicon layer, wherein the amorphous silicon layer is transformed into a crystalline silicon layer by the heat treatment. The removal of the oxide film on the surface of the amorphous silicon layer by performing the surface cleaning includes: spraying a hydrogen fluoride solution onto the surface of the amorphous silicon layer. The removal of the oxide film on the surface of the amorphous silicon layer by performing the surface cleaning further includes: performing a first rinsing cleaning, including supplying hydrogen water to the surface of the amorphous silicon layer in a free-fall manner, and then performing a second rinsing cleaning, including supplying hydrogen water to the surface of the amorphous silicon layer in a free-fall manner while applying vibration to the hydrogen water with mega-frequency ultrasound, wherein the first rinsing cleaning and the second rinsing cleaning do not include a spraying method, and No oxide solution is used in any of the steps from the step of forming a natural oxide on the surface of the amorphous silicon layer to the step of transforming the amorphous silicon layer into the crystalline silicon layer.

2. The method according to claim 1, wherein the hydrogen fluoride solution comprises 0.5 vol% hydrogen fluoride.

3. The method according to claim 1, wherein forming the active layer comprises: A laser beam is radiated onto the amorphous silicon layer disposed above the substrate, wherein the laser beam has a long side and a short side respectively in a first direction and a second direction perpendicular to each other; and The substrate is moved by a predetermined pitch in the second direction parallel to the short side.

4. The method according to claim 3, Whenever the substrate moves by the predetermined pitch, the laser beam is repeatedly turned on and off. The predetermined pitch is configured to allow the laser beam to be turned on at least 7 times in the cell region of the amorphous silicon layer.

5. The method according to claim 1, further comprising: A buffer layer is provided between the substrate and the amorphous silicon layer. The thickness of the amorphous silicon layer is in to Within the range, and The buffer layer includes a thickness of to SiO x .

6. A thin-film transistor substrate manufactured by the method of any one of claims 1 to 5, comprising: A substrate, an active layer above the substrate, a gate electrode facing the active layer, a source electrode connected to the active layer, and a drain electrode connected to the active layer. The surface of the active layer includes protrusions, and The height of the protrusion is 3 nm or less.

7. The thin-film transistor substrate according to claim 6, further comprising: A buffer layer between the substrate and the active layer. The thickness of the active layer is to Within the range, The buffer layer includes a thickness of to SiO x .

8. A method for manufacturing a display device, the method comprising: A thin-film transistor is provided above the substrate, and an organic light-emitting device connected to the thin-film transistor is provided. The provision of the thin-film transistor includes: An amorphous silicon layer is provided above the substrate; An oxide film is formed on the surface of the amorphous silicon layer without using an oxidation solution; The oxide film on the surface of the amorphous silicon layer is removed by surface cleaning without using an oxidation solution; and An active layer is formed by heat treatment on the amorphous silicon layer, wherein the amorphous silicon layer is transformed into a crystalline silicon layer by the heat treatment. The removal of the oxide film on the surface of the amorphous silicon layer by performing the surface cleaning includes: spraying a hydrogen fluoride solution onto the surface of the amorphous silicon layer. The removal of the oxide film on the surface of the amorphous silicon layer by performing the surface cleaning further includes: performing a first rinsing cleaning, including supplying hydrogen water to the surface of the amorphous silicon layer in a free-fall manner, and then performing a second rinsing cleaning, including supplying hydrogen water to the surface of the amorphous silicon layer in a free-fall manner while applying vibration to the hydrogen water with mega-frequency ultrasound, wherein the first rinsing cleaning and the second rinsing cleaning do not include a spraying method, and No oxide solution is used in any of the steps from the step of forming a natural oxide on the surface of the amorphous silicon layer to the step of transforming the amorphous silicon layer into the crystalline silicon layer.

9. The method according to claim 8, The hydrogen fluoride solution therein comprises 0.5 vol% hydrogen fluoride.

10. The method of claim 8, wherein forming the active layer comprises: A laser beam is radiated onto the amorphous silicon layer disposed above the substrate, wherein the laser beam has a long side and a short side respectively in a first direction and a second direction perpendicular to each other; and The substrate is moved by a predetermined pitch in the second direction parallel to the short side.

11. The method according to claim 10, Whenever the substrate moves by the predetermined pitch, the laser beam is repeatedly turned on and off, and The predetermined pitch is configured to allow the laser beam to be turned on at least 7 times in the cell region of the amorphous silicon layer.

12. The method of claim 8, further comprising: A buffer layer is provided between the substrate and the amorphous silicon layer. The thickness of the amorphous silicon layer is in to Within the range, and The buffer layer includes a thickness of to SiO x .

13. A display device manufactured by the method of any one of claims 8 to 12, comprising: Thin-film transistors above the substrate and organic light-emitting devices connected to the thin-film transistors. The thin-film transistor includes: an active layer above the substrate, a gate electrode facing the active layer, a source electrode connected to the active layer, and a drain electrode connected to the active layer. The surface of the active layer includes protrusions, and The height of the protrusion is 3 nm or less.

14. The display device according to claim 13, further comprising: A buffer layer between the substrate and the active layer. The thickness of the active layer is to Within the range, and The buffer layer includes a thickness of to SiO x .

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