CN109920796B - Film coating method of TFT substrate - Google Patents
Film coating method of TFT substrate Download PDFInfo
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- CN109920796B CN109920796B CN201711329187.XA CN201711329187A CN109920796B CN 109920796 B CN109920796 B CN 109920796B CN 201711329187 A CN201711329187 A CN 201711329187A CN 109920796 B CN109920796 B CN 109920796B
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Abstract
The invention discloses a film coating method of a TFT substrate, which comprises the steps of firstly uniformly mixing a boron hydride compound and a silicon-containing raw material in proportion, pressing the mixture on a substrate which is pre-plated with a buffer layer and the boron hydride compound, then introducing the silicon-containing raw material and hydrogen, and coating a film by a chemical vapor deposition method. Compared with the prior art, the invention adopts the coating method combining the chemical vapor deposition method and the spraying method, changes the original coating process of the TFT substrate, ensures that the dispersion of boron element in the prior art is more uniform, the structure of the film system is more uniform and complete, the whole coating process is more environment-friendly and efficient than the prior art, the manufacturing cost is low, the manufactured TFT substrate does not need to independently dope the channel, the preparation process is simple, the requirement on the environment is low, and the potential market value is realized.
Description
Technical Field
The invention relates to a film coating method of a TFT substrate, belonging to the field of chemical vapor deposition.
Background
With the popularization of portable mobile devices, flat panel displays have been widely used due to their thin and light bodies, low energy consumption, no radiation, and other advantages. The conventional flat panel Display mainly includes a Liquid Crystal Display (LCD) and an organic light emitting diode Display device. Compared with the LCD, the OLED has the advantages of no need of a backlight source, high contrast, thin thickness, wide viewing angle, fast response speed, wide application range, simple manufacture and the like, and gradually occupies the mainstream of the market. The OLED display device may be classified into a Passive Matrix OLED (PMOLED) and an Active Matrix OLED (AMOLED) according to a driving method. Each pixel of the AMOLED is provided with a low temperature polysilicon Thin Film Transistor (LTP-Si TFT) with a switching function, each pixel is provided with a charge storage capacitor, and a peripheral driving circuit and a display array whole system are integrated on the same glass substrate. The active drive belongs to a static drive mode, has a memory effect, can carry out 100 percent load drive, is not limited by the number of scanning electrodes, and can independently and selectively adjust each pixel. The active drive has no duty ratio problem, the drive is not limited by the number of scanning electrodes, and the high brightness and high resolution are easy to realize.
Another reason AMOLED can be widely used is that AMOLED screens can be made of flexible substrates, wearable devices are deeply developed, products are continuously new, and flexible display devices with flexible variability can bring about user subversive use experience. However, the prior art is still not very mature for the technology of preparing the flexible AMOLED screen, the thickness of the produced flexible AMOLED screen still does not reach an ideal level, and in order to ensure the insulation between the first metal layer and the second metal layer, the insulating layer has poor stress, and when the flexible AMOLED screen is bent, bad phenomena such as fracture and falling are more likely to occur, and further the reject ratio of the product is caused.
Basically, all TFT substrates are not high-temperature resistant, so the process of the TFT must be carried out at a relatively low temperature, the used silicon layer is an amorphous silicon layer or a polycrystalline silicon layer manufactured by using silicide gas, the development of the current display technology needs the TFT with higher performance to drive the LCD pixel and the AMOLED pixel, and the amorphous silicon TFT has the advantages of simple preparation process and good uniformity, but has lower mobility and can not meet the requirement on driving; although the low temperature polysilicon has high migration, the manufacturing cost is too high due to the need of laser-assisted annealing, and the mass production uniformity of polysilicon is poor, which cannot meet the requirement of large-area high-resolution display production.
A thin film transistor array substrate, i.e., a TFT substrate, is an important component of a liquid crystal display. In the TFT substrate, channel doping is required to adjust the threshold voltage of the device. A small amount of donor or acceptor impurities is ion-implanted into the channel region, typically after the gate oxide film is formed, by an ion implantation technique, to complete channel doping. In the ion implantation process, ion implantation is most commonly realized by an ion implanter, for example, a channel region, an N-type heavily doped region, an N-type lightly doped region, a P-type doped region and the like are generally implanted by the ion implanter, and each ion implantation process needs to be completed by using a photomask, and the ion implantation process has strict requirements on the precision of the photomask, and has the problems of difficult machine debugging, long time consumption and the like. The preparation process is precise and complex, and the production cost is high.
Disclosure of Invention
In view of the above problems of the prior art, the present invention is directed to a method for coating a TFT substrate.
In order to achieve the above object, the present invention adopts the following technical scheme:
the film coating method of the invention comprises the steps of firstly uniformly mixing the boron hydride and the silicon-containing raw material in proportion, pressing the mixture on a substrate which is pre-plated with the buffer layer and the boron hydride after mixing, then introducing the silicon-containing raw material and hydrogen, and coating the film by a chemical vapor deposition method.
Preferably, the coating method of the present invention is specifically as follows:
a) depositing a buffer layer on a substrate; the buffer layer is a silicon-containing buffer layer;
b) adding a borohydride into a film coating system to deposit a layer of borohydride on the buffer layer;
c) mixing a silicon-containing raw material and a boron hydride compound in proportion, taking ethanol as a solvent, adding the silicon-containing raw material, introducing the boron hydride compound, adding a foaming agent, a flatting agent and a thickening agent, mixing, introducing hydrogen, pressurizing, performing gradient heating to compact the mixture, and spraying the uniformly stirred mixed solution on the deposited boron hydride compound;
d) introducing a silicon-containing raw material and hydrogen, and depositing an amorphous silicon film on the film surface which is heated, pressurized and compacted by a chemical vapor deposition method;
e) annealing the amorphous silicon layer to remove hydrogen ions in the amorphous silicon layer;
f) performing ion implantation twice on the amorphous silicon layer doped with the boron ions by using two photomasks to obtain two N-type heavily doped regions positioned on two sides of the amorphous silicon layer, a boron ion doped channel region positioned in the middle of the amorphous silicon layer and two N-type lightly doped regions positioned between the two N-type heavily doped regions and the channel region;
g) sequentially forming a gate insulating layer, a gate, an interlayer insulating layer, a source and a drain on the amorphous silicon layer;
h) an insulating layer is deposited between the layers overlying the gate insulating layer.
Preferably, the substrate includes a rigid substrate including, but not limited to, a glass substrate, a plastic substrate, and a flexible substrate including, but not limited to, a polymer material substrate, such as a PI substrate.
Preferably, the silicon-containing starting material is silane.
Preferably, the borohydride is diborane (B)2H6). Silane and diborane are selected for coating, so that the coating effect is good, the raw materials are cheap and easy to obtain, the operation is simple, hydrogen ions are remained after the silane and the diborane are mixed and dissociated, the removal in the post-treatment process is convenient, and the whole coating effect is not influenced by bubbles or intermolecular distance change.
Preferably, the buffer layer is a silicon oxide (SiOx) layer, a silicon nitride (SiNx) layer, or a composite layer of a silicon oxide layer and a silicon nitride layer, and the insulating layer and the buffer layer are made of the same material and prepared by the same method.
Preferably, step c specifically comprises:
adding silane and diborane in a mass ratio of 3-10: 25, mixing, taking ethanol as a solvent, adding silane and introducing diborane, adding ammonium carbonate accounting for 12.5 percent of the solution system, polyacrylic acid accounting for 1 percent of the solution system and silicon dioxide accounting for 5 percent of the solution system, mixing, pressurizing and heating in a gradient manner to compact the mixture, pressurizing to 0.01Pa, heating at the speed of 1-5 ℃/min, heating to 150 ℃, keeping the temperature, introducing hydrogen, stirring and mixing uniformly, and spraying the uniformly stirred mixed solution on the deposited diborane.
The mixed solution of the dispersing agent and the leveling agent is added, so that a good doping effect is achieved, the potential difference between silane and diborane can be effectively reduced and the effect of boron element is enhanced compared with the existing layered annealing evaporation method for preparing the film after mixing, ethanol is volatile, the concentration of the mixed solution is high under the action of the leveling agent and the thickening agent, leveling is easy to achieve, and the effect of the film is guaranteed.
Before the mixed liquid is pressed on the substrate, the buffer layer and a layer of boron element are preset on the substrate, and the dispersing agent plays a good role in dispersion and penetration after pressing, so that the whole boron element is dispersed more uniformly in the silicon-containing film system.
Preferably, the step d further comprises at least one repeated coating step, specifically: introducing silicon-containing raw materials and hydrogen, depositing a layer of amorphous silicon film on the film surface which is heated, pressurized and compacted by a chemical vapor deposition method, repeating amorphous silicon film coating for at least one time to obtain at least three layers of amorphous silicon films, wherein the layer closest to the substrate is the amorphous silicon film doped with boron ions, and two layers of amorphous silicon films which are not doped with boron ions are sequentially coated to form an amorphous silicon layer in a superposed manner.
In order to ensure the using effect of the TFT substrate, the thickness of the amorphous silicon layer needs to be ensured, that is, the number of times of coating the amorphous silicon thin film is determined according to the thickness requirement of the amorphous silicon layer.
Preferably, when hydrogen ions are removed by annealing, the operation can be performed by referring to various annealing prior arts, and the operation is not limited herein, and the annealing and the hydrogen removal ensure the compactness and the crystal form of the film system on one hand and assist the uniform dispersion of the boron element on the other hand. If necessary, boron ions may be added during annealing for further doping.
The choice of silane and diborane is only one preferred embodiment of the present invention, and the choice of these two materials should not be construed as a limitation of the present invention, and any readily soluble materials that can provide the silicon element and the boron element should be included in the scope of the present invention.
The TFT substrate produced by the film coating method of the invention sequentially comprises the following structures from the substrate: the buffer layer, the amorphous silicon layer, the N-type middle doped region, the boron ion doped channel region, the N-type light doped region, the interlayer insulating layer, and the source electrode and the drain electrode which protrude out of the surface of the substrate.
Compared with the prior art, the invention adopts the coating method combining the chemical vapor deposition method and the spraying method, changes the original coating process of the TFT substrate, ensures that the dispersion of boron element in the prior art is more uniform, the structure of the film system is more uniform and complete, the whole coating process is more environment-friendly and efficient than the prior art, the manufacturing cost is low, the manufactured TFT substrate does not need to independently dope the channel, the preparation process is simple, the requirement on the environment is low, and the potential market value is realized.
Detailed Description
The following provides a more detailed and complete description of the method for coating a TFT substrate according to the present invention with reference to the following examples. The following examples are illustrative only and are not to be construed as limiting the invention.
The experimental procedures in the following examples are conventional unless otherwise specified. The experimental materials used in the following examples were all commercially available unless otherwise specified.
The TFT substrate of the invention comprises the following structures in sequence from the substrate: the buffer layer, the amorphous silicon layer, the N-type middle doped region, the boron ion doped channel region, the N-type light doped region, the interlayer insulating layer, and the source electrode and the drain electrode which protrude out of the surface of the substrate.
The film coating method of the TFT substrate comprises the following steps:
a) depositing a buffer layer on a glass substrate, a plastic substrate or a PI substrate; the buffer layer is a silicon oxide (SiOx) layer, a silicon nitride (SiNx) layer or a composite layer of a silicon oxide layer and a silicon nitride layer;
b) depositing a layer of diborane (B) on the buffer layer by adding diborane to the coating system2H6)；
c) Silane and diborane are mixed in a mass ratio of 5: 25, mixing, namely adding silane and introducing diborane into ethanol serving as a solvent, adding a solution system of 12.5 percent of foaming agent (ammonium carbonate), 1 percent of flatting agent (polyacrylic acid) and 5 percent of thickening agent (silicon dioxide), mixing, pressurizing and heating in a gradient manner to compact the mixture, pressurizing to 0.01Pa, heating at the speed of 1 ℃/min to 150 ℃, keeping the temperature, introducing hydrogen, stirring and mixing uniformly, and spraying the uniformly stirred mixed solution on the deposited diborane;
d) introducing silane and hydrogen, and depositing an amorphous silicon film on the film surface which is heated, pressurized and compacted by a chemical vapor deposition method;
e) repeating the previous step at least once to obtain at least three layers of amorphous silicon films, wherein one layer closest to the substrate is the amorphous silicon film doped with boron ions, two layers of amorphous silicon films not doped with boron ions are sequentially plated, and the amorphous silicon layers are formed by superposition;
f) annealing the amorphous silicon layer to remove hydrogen ions in the amorphous silicon layer, wherein the amorphous silicon layer can be annealed by a furnace tube, Excimer Laser Annealing (ELA) equipment, Flash Lamp Annealing (FLA) equipment or chemical vapor deposition heating;
g) performing ion implantation twice on the amorphous silicon layer doped with the boron ions by using two photomasks to obtain two N-type heavily doped regions positioned on two sides of the amorphous silicon layer, a boron ion doped channel region positioned in the middle of the amorphous silicon layer and two N-type lightly doped regions positioned between the two N-type heavily doped regions and the channel region;
h) sequentially forming a gate insulating layer, a gate, an interlayer insulating layer, a source and a drain on the amorphous silicon layer;
i) and arranging an insulating layer between the layers covering the grid electrode on the grid electrode insulating layer, wherein the insulating layer and the buffer layer have the same composition and preparation process.
Finally, it must be said here that: the above embodiments are only used for further detailed description of the technical solutions of the present invention, and should not be understood as limiting the scope of the present invention, and the insubstantial modifications and adaptations made by those skilled in the art according to the above descriptions of the present invention are within the scope of the present invention.
Claims (7)
1. A film coating method of TFT base plate, characterized by that, the film coating method mixes boron hydrogen compound and raw materials of silicon-containing proportionally, press on the base plate plated with buffer layer and boron hydrogen compound already in advance after mixing, and then introduce raw materials of silicon-containing and hydrogen, the chemical vapor deposition method is plated a film;
the coating method specifically comprises the following steps:
a) depositing a buffer layer on a substrate; the buffer layer is a silicon-containing buffer layer;
b) adding a borohydride into a film coating system to deposit a layer of borohydride on the buffer layer;
c) mixing a silicon-containing raw material and a boron hydride compound in proportion, taking ethanol as a solvent, adding the silicon-containing raw material, introducing the boron hydride compound, adding a foaming agent, a flatting agent and a thickening agent, mixing, introducing hydrogen, pressurizing, performing gradient heating to compact the mixture, and spraying the uniformly stirred mixed solution on the deposited boron hydride compound;
d) introducing silicon-containing raw materials and hydrogen, depositing at least three layers of amorphous silicon films on the film surface which is heated, pressurized and compacted by a chemical vapor deposition method, wherein the layer closest to the substrate is the amorphous silicon film doped with boron ions, and sequentially plating two layers of amorphous silicon films not doped with boron ions to form an amorphous silicon layer in a superposed manner;
e) annealing the amorphous silicon layer to remove hydrogen ions in the amorphous silicon layer;
f) using two photomasks to carry out ion implantation twice on the amorphous silicon layer doped with boron ions, so as to obtain two N-type heavily doped regions positioned on two sides of the amorphous silicon layer, a boron ion doped channel region positioned in the middle of the amorphous silicon layer, and two N-type lightly doped regions positioned between the two N-type heavily doped regions and the channel region;
g) sequentially forming a gate insulating layer, a gate, an interlayer insulating layer, a source and a drain on the amorphous silicon layer;
h) an insulating layer is deposited between the layers overlying the gate insulating layer.
2. The method for coating a TFT substrate according to claim 1, wherein the step c specifically comprises:
adding silane and diborane in a mass ratio of 3-10: 25, mixing, taking ethanol as a solvent, adding silane and introducing diborane, adding ammonium carbonate accounting for 12.5 percent of the solution system, polyacrylic acid accounting for 1 percent of the solution system and silicon dioxide accounting for 5 percent of the solution system, mixing, pressurizing to 0.01Pa, heating at a gradient heating rate of 1-5 ℃/min, heating to 150 ℃, keeping the temperature, introducing hydrogen, stirring and mixing uniformly, and spraying the uniformly stirred mixed solution on the deposited diborane.
3. The method of claim 1, wherein step d further comprises at least one repeated coating step, specifically: introducing silicon-containing raw materials and hydrogen, depositing a layer of amorphous silicon film on the film surface which is heated, pressurized and compacted by a chemical vapor deposition method, and repeating amorphous silicon film coating at least once to obtain at least three layers of amorphous silicon films.
4. The method of plating a TFT substrate as set forth in claim 1, wherein: the buffer layer is a silicon oxide layer, a silicon nitride layer or a composite layer of the silicon oxide layer and the silicon nitride layer.
5. The method of plating a TFT substrate as set forth in claim 1, wherein: the substrate includes a rigid substrate and a flexible substrate.
6. The method of plating a TFT substrate as set forth in claim 1, wherein: the silicon-containing raw material is silane.
7. The method of plating a TFT substrate as set forth in claim 1, wherein: the borohydride compound is diborane.
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH04192530A (en) * | 1990-11-27 | 1992-07-10 | Fujitsu Ltd | Manufacture of thin film transistor and liquid crystal display panel |
| CN1297582A (en) * | 1999-03-30 | 2001-05-30 | 精工爱普生株式会社 | Method for mfg. thin-film transistor |
| CN1579009A (en) * | 2002-04-22 | 2005-02-09 | 精工爱普生株式会社 | Methods of manufacturing thin-film device and transistor, electro-optical device, and electronic equipment |
| CN105070686A (en) * | 2015-08-20 | 2015-11-18 | 深圳市华星光电技术有限公司 | Structure and preparation method of TFT substrate |
| CN105140128A (en) * | 2015-09-08 | 2015-12-09 | 信利（惠州）智能显示有限公司 | Low-temperature polycrystalline silicon thin film transistor and preparation method thereof |
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Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH04192530A (en) * | 1990-11-27 | 1992-07-10 | Fujitsu Ltd | Manufacture of thin film transistor and liquid crystal display panel |
| CN1297582A (en) * | 1999-03-30 | 2001-05-30 | 精工爱普生株式会社 | Method for mfg. thin-film transistor |
| CN1579009A (en) * | 2002-04-22 | 2005-02-09 | 精工爱普生株式会社 | Methods of manufacturing thin-film device and transistor, electro-optical device, and electronic equipment |
| CN105070686A (en) * | 2015-08-20 | 2015-11-18 | 深圳市华星光电技术有限公司 | Structure and preparation method of TFT substrate |
| CN105140128A (en) * | 2015-09-08 | 2015-12-09 | 信利（惠州）智能显示有限公司 | Low-temperature polycrystalline silicon thin film transistor and preparation method thereof |
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