WO2019205440A1 - Tft基板的制作方法及tft基板 - Google Patents

Tft基板的制作方法及tft基板 Download PDF

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WO2019205440A1
WO2019205440A1 PCT/CN2018/105626 CN2018105626W WO2019205440A1 WO 2019205440 A1 WO2019205440 A1 WO 2019205440A1 CN 2018105626 W CN2018105626 W CN 2018105626W WO 2019205440 A1 WO2019205440 A1 WO 2019205440A1
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layer
buffer layer
transparent conductive
buffer
source
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PCT/CN2018/105626
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English (en)
French (fr)
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颜源
李立胜
宋德伟
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武汉华星光电技术有限公司
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Priority to US16/097,838 priority Critical patent/US10964790B1/en
Publication of WO2019205440A1 publication Critical patent/WO2019205440A1/zh

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    • H01L29/40—Electrodes ; Multistep manufacturing processes therefor
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    • H01L29/417—Electrodes ; Multistep manufacturing processes therefor characterised by their shape, relative sizes or dispositions carrying the current to be rectified, amplified or switched
    • H01L29/41725—Source or drain electrodes for field effect devices
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    • H01L27/1259—Multistep manufacturing methods
    • H01L27/127—Multistep manufacturing methods with a particular formation, treatment or patterning of the active layer specially adapted to the circuit arrangement
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    • H01L27/1259—Multistep manufacturing methods
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    • H01L29/66409—Unipolar field-effect transistors
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    • H01L29/66742—Thin film unipolar transistors
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    • H01L29/66—Types of semiconductor device ; Multistep manufacturing processes therefor
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    • H01L29/76—Unipolar devices, e.g. field effect transistors
    • H01L29/772—Field effect transistors
    • H01L29/78—Field effect transistors with field effect produced by an insulated gate
    • H01L29/786—Thin film transistors, i.e. transistors with a channel being at least partly a thin film
    • H01L29/78606—Thin film transistors, i.e. transistors with a channel being at least partly a thin film with supplementary region or layer in the thin film or in the insulated bulk substrate supporting it for controlling or increasing the safety of the device
    • H01L29/78618—Thin film transistors, i.e. transistors with a channel being at least partly a thin film with supplementary region or layer in the thin film or in the insulated bulk substrate supporting it for controlling or increasing the safety of the device characterised by the drain or the source properties, e.g. the doping structure, the composition, the sectional shape or the contact structure
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    • H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic Table or AIIIBV compounds with or without impurities, e.g. doping materials
    • H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
    • H01L21/31—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26 to form insulating layers thereon, e.g. for masking or by using photolithographic techniques; After treatment of these layers; Selection of materials for these layers
    • H01L21/3105—After-treatment
    • H01L21/311—Etching the insulating layers by chemical or physical means
    • H01L21/31105—Etching inorganic layers
    • H01L21/31111—Etching inorganic layers by chemical means
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    • H01L29/66—Types of semiconductor device ; Multistep manufacturing processes therefor
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    • H01L29/76—Unipolar devices, e.g. field effect transistors
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Definitions

  • the present invention relates to the field of display technologies, and in particular, to a method for fabricating a TFT substrate and a TFT substrate.
  • flat panel display devices such as liquid crystal display (LCD) and active matrix organic light-emitting diode (AMOLED) displays have thin body and high image quality. Power saving, no radiation and many other advantages have been widely used, such as mobile phones, personal digital assistants (PDAs), digital cameras, computer screens or notebook screens.
  • LCD liquid crystal display
  • AMOLED active matrix organic light-emitting diode
  • Thin Film Transistor (TFT) Array (Array) substrate is the main component of current LCD devices and AMOLED devices. It is directly related to the development direction of high-performance flat panel display devices. It is used to provide driving circuits to displays.
  • the source and drain of the thin film transistor are turned on, thereby inputting the data voltage on the data line to the pixel electrode, thereby controlling the corresponding pixel region. display.
  • the structure of the thin film transistor on the array substrate further includes a gate electrode, a gate insulating layer, an active layer, a source and a drain, and an insulating protective layer which are stacked on the substrate.
  • LTPS Low Temperature Poly-Silicon
  • A-Si amorphous silicon
  • in-cell touch structure In Cell Touch
  • a film layer with a touch function In order to satisfy the functions of display and touch, each layer needs to be completed.
  • the cover and the etching form a certain pattern.
  • the source and drain electrodes are shared by the interlayer insulating layer (ILD) layer and the flat layer (PLN), and the common electrode layer (BITO) and the pixel electrode layer (TITO) are exchanged.
  • SD the touch line and the pixel electrode share a Half Tone Mask (HTM), which can omit two Mask processes, realize 7 light mask process technology, and produce LTPS low temperature with In Cell Touch function.
  • HTM Half Tone Mask
  • Polysilicon array substrate In the 7Mask process, after the source drain and the pixel electrode share the mask, the source and drain must pass indium tin oxide (ITO) to indirectly contact the source-drain contact region of the active layer, and the polysilicon contacts the indium tin oxide.
  • ITO indium tin oxide
  • the Schottky contact barrier will have a current limiting effect and the TFT device mobility will drop significantly.
  • An object of the present invention is to provide a method for fabricating a TFT substrate, which avoids the Schottky contact barrier which occurs when polysilicon is in contact with indium tin oxide in the 7Mask technique, so that the source and drain are directly from the source and the source and drain of the active layer from below.
  • the polar contact regions form an ohmic contact, which increases the electron mobility of the TFT device.
  • the region forms an ohmic contact and increases the electron mobility of the TFT device.
  • the present invention first provides a method for fabricating a TFT substrate, comprising the following steps:
  • Step S1 providing a base substrate, and forming a buffer layer, an active layer, a gate insulating layer, an interlayer insulating layer, and a flat layer disposed in this order from bottom to top on the base substrate;
  • the active layer has a source-drain contact region at both ends and a channel region in the middle, and the active layer is respectively provided with a contact via via on the source-drain contact regions at both ends;
  • Step S2 exposing and developing the flat layer, forming a photoresist via hole on the flat layer corresponding to the via hole of the contact region, using the flat layer as a shielding layer, and the interlayer insulating layer,
  • the gate insulating layer and the buffer layer are etched for the first time, and an insulating layer via hole communicating with the via hole of the contact region is formed on the interlayer insulating layer and the gate insulating layer, and the contact region is formed on the buffer layer a buffer layer groove in which the holes are connected;
  • Step S3 performing a second etching on the buffer layer, so that the buffer layer is laterally etched at the buffer layer recess, so that an undercut structure is formed between the buffer layer recess and the active layer at the contact region via;
  • Step S4 sequentially depositing a transparent conductive layer and a metal layer over the interlayer insulating layer, the transparent conductive layer is broken at a via hole of the contact region, and the metal layer continuously extends into the buffer layer groove and fills the buffer. a layer recess, patterning the transparent conductive layer and the metal layer, forming a source drain and a touch line from the metal layer, forming a pixel electrode from the transparent conductive layer, wherein the source drain passes through the buffer layer recess from below Contacting the source and drain contact regions of the active layer.
  • the method for fabricating the TFT substrate further includes the step S5 of forming a passivation layer covering the transparent conductive layer and the metal layer on the interlayer insulating layer, and depositing and patterning the common electrode layer on the passivation layer.
  • the material of the transparent conductive layer is indium tin oxide.
  • the buffer layer is a combination of a silicon oxide layer and a silicon nitride layer, wherein the silicon oxide layer is stacked on the silicon nitride layer, and the buffer layer recess formed in the step S2 belongs to the silicon oxide layer.
  • the refractive index of the silicon oxide layer in the buffer layer is.
  • the pair of interlayer insulating layer, the gate insulating layer and the buffer layer are first etched by dry etching, and the etching gas used for the first etching includes carbon tetrafluoride.
  • the buffer layer is etched a second time by dry etching, and the etching gas used for performing the second etching includes pentafluoroethane.
  • the step S4 specifically includes the following steps:
  • Step S41 sequentially depositing a transparent conductive layer and a metal layer, forming a photoresist layer on the surface of the metal layer, exposing the photoresist layer using a halftone mask, and further developing the photoresist layer to obtain light.
  • Step S42 using the photoresist pattern as a shielding layer, performing the first etching on the transparent conductive layer and the metal layer, respectively, and obtaining a transparent transparent conductive pattern and a metal pattern respectively from the transparent conductive layer and the metal layer, the metal pattern including the target a metal pattern and a metal pattern to be removed, the transparent conductive pattern including a remaining conductive pattern and a target conductive pattern respectively corresponding to the target metal pattern and the metal pattern to be removed, the target metal pattern including a source drain and a touch line
  • the target conductive pattern includes a pixel electrode;
  • Step S43 removing the photoresist pattern corresponding to the metal pattern to be removed by the ashing process, performing a second etching on the metal layer, removing the metal pattern to be removed, and exposing the target conductive pattern.
  • the present invention also provides a TFT substrate comprising a base substrate, a buffer layer on the base substrate, an active layer on the buffer layer, a gate insulating layer covering the active layer on the buffer layer, and a gate insulating layer a gate on the layer, an interlayer insulating layer covering the gate on the gate insulating layer, a transparent conductive layer above the interlayer insulating layer, and a metal layer on the transparent conductive layer;
  • the active layer has a source-drain contact region at both ends and a channel region in the middle, and the active layer is respectively provided with a contact via via on the source-drain contact regions at both ends;
  • the interlayer insulating layer and the gate insulating layer are provided with an insulating layer via hole communicating with the via hole of the contact region, and the buffer layer is provided with a buffer layer groove communicating with the via hole of the contact region, and the buffer layer groove Forming an undercut structure between the active layer and the via hole at the contact area;
  • the transparent conductive layer is broken at a via hole of the contact region, and the metal layer continuously extends into the buffer layer recess and fills the buffer layer recess, the metal layer includes a source drain and a touch line, and the source and drain The pole is in contact with the source-drain contact region of the active layer from below through the buffer layer recess.
  • the TFT substrate further includes a light shielding layer disposed between the base substrate and the buffer layer, a passivation layer covering the transparent conductive layer and the metal layer, and a common electrode layer disposed on the passivation layer;
  • the transparent conductive material is indium tin oxide
  • the active layer is a low temperature polysilicon semiconductor layer.
  • the TFT substrate of the present invention is provided with a contact region via hole in a source-drain contact region at both ends of the active layer, and a buffer layer is formed under the via hole corresponding to the contact region of the buffer layer. a groove, and an undercut structure is formed between the buffer layer groove and the active layer at the via hole of the contact region, so that the transparent conductive layer is broken at the via hole of the contact region, and then the source and drain electrodes are passed through the insulating layer.
  • the via and the contact via are in contact with the source-drain contact region of the active layer from below in the buffer layer recess, avoiding the Schottky contact barrier of the polysilicon in contact with the indium tin oxide in the 7Mask technique,
  • the source drain directly forms an ohmic contact with the source-drain contact region of the active layer from below, which improves the electron mobility of the TFT device.
  • the source/drain contact regions at both ends of the active layer are respectively provided with contact region via holes
  • the buffer layer is provided with a buffer layer groove corresponding to the contact region via the via hole, and the buffer layer groove and the buffer layer
  • An undercut structure is formed between the source layers at the via hole of the contact region, so that the transparent conductive layer is broken at the via hole of the contact region, and then the source and drain holes are passed through the insulating layer via hole and the contact region via hole is in the buffer layer groove.
  • the drain contact region forms an ohmic contact, which increases the electron mobility of the TFT device.
  • FIG. 1 is a schematic flow chart of a method of fabricating a TFT substrate of the present invention
  • FIG. 2 is a schematic view showing a step S1 of a method of fabricating a TFT substrate of the present invention
  • step S1 of the method for fabricating a TFT substrate of the present invention is a schematic plan view showing an active layer formed in step S1 of the method for fabricating a TFT substrate of the present invention
  • FIG. 4 is a schematic structural view of a film layer at a via hole of a contact region in step S1 of the method for fabricating a TFT substrate of the present invention
  • FIG. 5 is a schematic view showing a step S2 of a method of fabricating a TFT substrate of the present invention
  • FIG. 6 is a schematic structural view of a film layer at a via hole of a contact region in step S2 of the method for fabricating a TFT substrate of the present invention
  • FIG. 7 is a schematic view showing a step S3 of a method of fabricating a TFT substrate of the present invention.
  • FIG. 8 is a schematic structural view of a film layer at a via hole of a contact region in step S3 of the method for fabricating a TFT substrate of the present invention.
  • FIG. 9 is a schematic view showing a step S4 of a method of fabricating a TFT substrate of the present invention.
  • FIG. 10 is a schematic view showing a step of breaking a transparent conductive layer at a via hole of a contact region in step S4 of the method for fabricating a TFT substrate of the present invention
  • FIG. 11 is a schematic view showing the source and drain contacts the active layer from below in the buffer layer recess in step S4 of the method for fabricating the TFT substrate of the present invention
  • Fig. 12 is a schematic view showing a step S5 of the method for fabricating a TFT substrate of the present invention and a schematic structural view of the TFT substrate of the present invention.
  • the present invention first provides a method for fabricating a TFT substrate, including the following steps:
  • Step S1 as shown in FIG. 2, the base substrate 10 is provided, and the light shielding layer 15 on the base substrate 10, the buffer layer 20 covering the light shielding layer 15 on the base substrate 10, and the buffer layer 20 are sequentially formed.
  • the active layer 30 has a source-drain contact region 31 at both ends and a channel region 32 between the two source-drain contact regions 31 in the middle.
  • the layer 30 is provided with a contact via 35 on each of the source and drain contact regions 31 at both ends.
  • the buffer layer 20 is a combination of a silicon oxide (SiOx) layer and a silicon nitride (SiNx) layer, wherein the silicon oxide layer is stacked on the silicon nitride layer.
  • the gate insulating layer 40 is a silicon oxide layer
  • the interlayer insulating layer 60 is a combination of a silicon oxide layer and a silicon nitride layer.
  • the active layer 30 is a low temperature polysilicon semiconductor layer.
  • Step S2 as shown in FIG. 5, exposing and developing the flat layer 70, forming a photoresist via 75 on the flat layer 70 corresponding to the contact region via 35, to the flat layer 70 is a shielding layer, and the interlayer insulating layer 60, the gate insulating layer 40, and the buffer layer 20 are first etched.
  • the interlayer insulating layer is insulated corresponding to the contact region via 35.
  • An insulating layer via 65 communicating with the contact via 35 and the photoresist via 75 is formed on the layer 60 and the gate insulating layer 40, and is formed on the buffer layer 20 corresponding to the underside of the contact via 35.
  • the buffer hole 25 is in contact with the via hole 35 of the contact region.
  • the pair of interlayer insulating layer 60, the gate insulating layer 40, and the buffer layer 20 are first etched by dry etching, and the etching gas used for the first etching is performed.
  • etching gas used for the first etching is performed.
  • CF 4 carbon tetrafluoride
  • the buffer layer groove 25 formed in the step S2 belongs to the silicon oxide layer of the buffer layer 20.
  • Step S3 as shown in FIG. 7, the buffer layer 20 is etched a second time, so that the buffer layer 20 is laterally etched at the buffer layer groove 25, as shown in FIG. 8, so that the width of the buffer layer groove 25 is made.
  • the enlargement further forms an undercut structure between the buffer layer recess 25 and the active layer 30 at the contact region via 35.
  • the buffer layer 20 is etched a second time by dry etching in the step S3.
  • the silicon oxide layer of the buffer layer 20 formed in the step S1 is a loose structure having a refractive index of 1.40 to 1.47, and the refractive index of the silicon oxide layer of the normal structure is usually greater than 1.49, for example, the interlayer insulating layer 60 is a silicon oxide layer; and the etching gas used in the second etching in the step S3 has selective etching property on the buffer layer 20, the etching gas containing pentafluoroethane such that the buffer layer 20 is in the buffer layer groove 25 can be laterally etched, thereby forming an undercut structure between the buffer layer recess 25 and the active layer 30
  • Step S4 as shown in FIG. 9, a transparent conductive layer 7 and a metal layer 8 are sequentially deposited over the interlayer insulating layer 60.
  • the transparent conductive layer 7 occurs at the contact region via 35. Breaking, the metal layer 8 continuously extends into the buffer layer recess 25 and fills the buffer layer recess 25, and the transparent conductive layer 7 and the metal layer 8 are patterned, and the source and drain electrodes 81 are formed by the metal layer 8 and The touch line 82 is formed of a transparent conductive layer 7 to form a pixel electrode 71.
  • the source and drain electrodes 81 are separated from the source/drain contact region 31 of the active layer 30 from below by a buffer layer recess 25. contact.
  • the material of the transparent conductive layer 7 is indium tin oxide.
  • the preparation of the interlayer insulating layer 60 and the planarization layer 70 in the 9mask technique requires two mask processes, but in the 7mask technique of the present invention, the planarization layer 70 is used as the photoresist layer of the interlayer insulating layer 60.
  • the step S4 peels the flat layer 70 before depositing the transparent conductive layer 7 and the metal layer 8, and only through a mask process
  • the preparation of the interlayer insulating layer 70 is completed, thereby saving a mask process relative to the 9mask process; the transparent conductive layer 7 and the metal layer 8 are formed on the surface of the interlayer insulating layer 60.
  • the flat layer 70 may be left in the step S4, and the transparent conductive layer 7 and the metal layer 8 are formed on the surface of the flat layer 70.
  • the step S4 performs a patterning process on the transparent conductive layer 7 and the metal layer 8 by using a halftone mask.
  • the step S4 specifically includes the following steps:
  • Step S41 sequentially depositing a transparent conductive layer 7 and a metal layer 8, forming a photoresist layer on the surface of the metal layer 8, and exposing the photoresist layer using a halftone mask, thereby developing the photoresist layer. , to obtain a photoresist pattern.
  • the transparent conductive layer 7 and the metal layer 8 are first etched by using the photoresist pattern as a shielding layer, and the transparent conductive layer 7 and the metal layer 8 respectively obtain overlapping transparent conductive patterns and metal patterns.
  • the metal pattern includes a target metal pattern and a metal pattern to be separated, the transparent conductive pattern including a remaining conductive pattern and a target conductive pattern respectively corresponding to the target metal pattern and the underlying metal pattern, wherein the target metal pattern includes a source
  • the target conductive pattern includes the pixel electrode 71, and the thickness of the photoresist pattern above the metal pattern to be removed is smaller than the thickness of the photoresist pattern above the target metal pattern.
  • step S43 the photoresist pattern corresponding to the upper portion of the metal pattern to be removed is removed by an ashing process, and the metal layer 8 is etched a second time to remove the metal pattern to be removed to expose the target conductive pattern.
  • Step S5 as shown in FIG. 12, a passivation layer 90 covering the transparent conductive layer 7 and the metal layer 8 is formed on the interlayer insulating layer 60, and a common electrode layer is deposited and patterned on the passivation layer 90. 95.
  • the contact vias 35 are respectively disposed in the source-drain contact regions 31 at both ends of the active layer 30, and the buffer layer 20 is formed under the vias 35 corresponding to the contact regions.
  • the groove 25 forms an undercut structure between the buffer layer groove 25 and the active layer 30 at the contact region via 35, so that the transparent conductive layer 7 is broken at the contact region via 35, and subsequently the source and drain are made.
  • the occurrence of the Schottky contact barrier causes the source and drain electrodes 81 to form an ohmic contact directly with the source-drain contact region 31 of the active layer 30 from below, thereby improving the electron mobility of the TFT device.
  • the present invention further provides a TFT substrate including a base substrate 10, a light shielding layer 15 on the base substrate 10, and a buffer layer 20 covering the light shielding layer 15 on the base substrate 10,
  • the active layer 30 has a source and drain contact region 31 at both ends and a channel region 32 in the middle, the active layer 30 is provided with a contact via 35 on each of the source and drain contact regions 31 at both ends;
  • An insulating layer via 65 communicating with the via hole 35 of the contact region is disposed on the interlayer insulating layer 60 and the gate insulating layer 40, and the buffer layer 20 is provided with a buffer layer concave communicating with the via hole 35 of the contact region. a groove 25, and an undercut structure is formed between the buffer layer groove 25 and the active layer 30 at the contact region via 35;
  • the transparent conductive layer 7 is broken at the contact region via 35, and the transparent conductive layer 7 includes a pixel electrode 71, and the metal layer 8 continuously extends into the buffer layer recess 25 and fills the buffer layer recess 25,
  • the metal layer 8 includes a source drain 81 and a touch line 82.
  • the source drain 81 is in contact with the source-drain contact region 31 of the active layer 30 from below through the buffer layer recess 25 .
  • the material of the transparent conductive layer 7 is indium tin oxide.
  • the active layer 30 is a low temperature polysilicon semiconductor layer.
  • the source/drain contact regions 31 at both ends of the active layer 30 are respectively provided with contact region vias 35, and the buffer layer 20 is provided with a buffer layer recess 25 corresponding to the contact region via holes 35, and An undercut structure is formed between the buffer layer recess 25 and the active layer 30 at the contact region via 35 such that the transparent conductive layer 7 is broken at the contact region via 35, and subsequently the source and drain electrodes 81 pass through the insulating layer.
  • the hole 65 and the contact region via 35 are in contact with the source-drain contact region 31 of the active layer 30 from below in the buffer layer recess 25, avoiding the Schottky which occurs when the polysilicon is in contact with the indium tin oxide in the 7Mask technique.
  • the contact barrier is such that the source and drain electrodes 81 directly form an ohmic contact with the source-drain contact region 31 of the active layer 30 from below, improving the electron mobility of the TFT device.
  • the TFT substrate of the present invention is formed by separately providing contact vias in the source-drain contact regions at both ends of the active layer, and forming a buffer layer recess under the vias corresponding to the vias of the contact regions. a trench, and an undercut structure is formed between the buffer layer recess and the active layer at the via hole of the contact region, so that the transparent conductive layer is broken at the via hole of the contact region, and then the source and drain electrodes are passed through the insulating layer via hole.
  • the contact region via hole contacts the source-drain contact region of the active layer from below in the buffer layer recess, avoiding the Schottky contact barrier which occurs when the polysilicon is in contact with the indium tin oxide in the 7Mask technique, so that the source The drain directly forms an ohmic contact with the source-drain contact region of the active layer from below, which improves the electron mobility of the TFT device.
  • the source/drain contact regions at both ends of the active layer are respectively provided with contact region via holes
  • the buffer layer is provided with a buffer layer groove corresponding to the contact region via the via hole, and the buffer layer groove and the buffer layer
  • An undercut structure is formed between the source layers at the via hole of the contact region, so that the transparent conductive layer is broken at the via hole of the contact region, and then the source and drain holes are passed through the insulating layer via hole and the contact region via hole is in the buffer layer groove.
  • the drain contact region forms an ohmic contact, which increases the electron mobility of the TFT device.

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Abstract

一种TFT基板的制作方法及TFT基板。制作方法包括：通过在有源层（30）两端的源漏极接触区（31）内分别设置接触区过孔（35），在缓冲层（20）对应于所述接触区过孔（35）下方形成缓冲层凹槽（25），并使缓冲层凹槽（25）和有源层（30）之间在接触区过孔（35）处形成底切结构，从而使得透明导电层（7）在接触区过孔（35）处发生断裂，后续使得源漏极（81）穿过绝缘层过孔（65）和接触区过孔（35）在缓冲层凹槽（25）内从下方与有源层（30）的源漏极接触区（31）相接触，避开了7Mask技术中多晶硅与氧化铟锡接触而出现的肖特基接触势垒，使得源漏极（81）从下方直接与有源层（30）的源漏极接触区（31）形成欧姆接触，提高了TFT器件的电子迁移率。

Description

TFT基板的制作方法及TFT基板 技术领域
本发明涉及显示技术领域，尤其涉及一种TFT基板的制作方法及TFT基板。
背景技术
在显示技术领域，液晶显示器(Liquid Crystal Display，LCD)和有源矩阵驱动式有机电致发光(Active Matrix Organic Light-Emitting Diode，AMOLED)显示器等平板显示装置因具有机身薄、高画质、省电、无辐射等众多优点，得到了广泛的应用，如：移动电话、个人数字助理(PDA)、数字相机、计算机屏幕或笔记本屏幕等。
薄膜晶体管(Thin Film Transistor，TFT)阵列(Array)基板是目前LCD装置和AMOLED装置中的主要组成部件，直接关系到高性能平板显示装置的发展方向，用于向显示器提供驱动电路，通常设置有数条栅极扫描线和数条数据线，该数条栅极扫描线和数条数据线限定出多个像素单元，每个像素单元内设置有薄膜晶体管和像素电极，薄膜晶体管的栅极与相应的栅极扫描线相连，当栅极扫描线上的电压达到开启电压时，薄膜晶体管的源极和漏极导通，从而将数据线上的数据电压输入至像素电极，进而控制相应像素区域的显示。通常阵列基板上薄膜晶体管的结构又包括层叠设置于衬底基板上的栅极、栅极绝缘层、有源层、源漏极、及绝缘保护层。
其中，低温多晶硅(Low Temperature Poly-Silicon，LTPS)薄膜晶体管与
传统非晶硅(A-Si)薄膜晶体管相比，虽然制作工艺复杂，但因其具有更高的载流子迁移率，被广泛用于中小尺寸高分辨率的LCD和AMOLED显示面板的制作，低温多晶硅被视为实现低成本全彩平板显示的重要材料。
鉴于低温多晶硅技术的有源矩阵朝着不断缩小尺寸方向发展，随之而来的光刻技术进步导致了生产设备成本的激增。常见的导入内嵌式触控结构(In Cell Touch)是将具有触控功能的膜层穿插在正常显示的阵列制程中，为了满足显示与触控的功能同时可用，每一层都需要完成光罩、蚀刻形成一定的图案。导入内嵌式触控阵列基板需要使用12道光罩(mask)工艺进行制作，这样增加了阵列工艺中曝光机的使用，进而增加了阵列制程的复 杂性，致使阵列基板整体的产能降低，为了降低制造成本，本行业内发明了9道光罩工艺进行阵列基板的制作，但是这还是不能满足对阵列基板日益增加的产能的需求。
在9Mask技术的基础上，通过将层间绝缘层(ILD)层和平坦层(PLN)共用一道光罩，并使公共电极层(BITO)与像素电极层(TITO)位置交换后，源漏极(SD)、触控线与像素电极共用一道半色调光罩(Half Tone Mask，HTM)制作形成，可省略两道Mask工艺，实现7道光光罩工艺技术，制作具有In Cell Touch功能的LTPS低温多晶硅阵列基板。但是7Mask工艺中，源漏极与像素电极共用光罩后，源漏极必须通过氧化铟锡(ITO)才能与有源层的源漏极接触区发生间接接触，多晶硅与氧化铟锡接触而出现的肖特基接触势垒，会产生限流效应，TFT器件迁移率大幅下降。
发明内容
本发明的目的在于提供一种TFT基板的制作方法，避开了7Mask技术中多晶硅与氧化铟锡接触而出现的肖特基接触势垒，使得源漏极从下方直接与有源层的源漏极接触区形成欧姆接触，提高TFT器件的电子迁移率。
本发明的目的还在于提供一种TFT基板，避开了7Mask技术中多晶硅与氧化铟锡接触而出现的肖特基接触势垒，使得源漏极从下方直接与有源层的源漏极接触区形成欧姆接触，提高TFT器件的电子迁移率。
为实现上述目的，本发明首先提供一种TFT基板的制作方法，包括如下步骤：
步骤S1、提供衬底基板，并在衬底基板上形成由下至上依次设置的缓冲层、有源层、栅极绝缘层、层间绝缘层及平坦层；
所述有源层具有位于两端的源漏极接触区及位于中间的沟道区，所述有源层在两端的源漏极接触区上分别设有一接触区过孔；
步骤S2、对所述平坦层进行曝光、显影，在所述平坦层上对应于所述接触区过孔的上方形成光阻过孔，以所述平坦层为遮蔽层，对层间绝缘层、栅极绝缘层及缓冲层进行第一次蚀刻，在所述层间绝缘层和栅极绝缘层上形成与接触区过孔连通的绝缘层过孔，在所述缓冲层上形成与接触区过孔连通的缓冲层凹槽；
步骤S3、对所述缓冲层进行第二次蚀刻，使得缓冲层在缓冲层凹槽处被横向蚀刻，使缓冲层凹槽和有源层之间在接触区过孔处形成底切结构；
步骤S4、在所述层间绝缘层上方依次沉积形成透明导电层和金属层，所述透明导电层在接触区过孔处发生断裂，所述金属层连续伸入缓冲层凹 槽内并填充缓冲层凹槽，对所述透明导电层和金属层进行图案化处理，由金属层形成源漏极及触控线，由透明导电层形成像素电极，所述源漏极通过缓冲层凹槽从下方与所述有源层的源漏极接触区相接触。
所述的TFT基板的制作方法还包括步骤S5、在所述层间绝缘层上形成覆盖透明导电层和金属层的钝化层，在所述钝化层上沉积并图案化形成公共电极层。
所述透明导电层的材料为氧化铟锡。
所述缓冲层为氧化硅层与氮化硅层的组合，其中氧化硅层堆叠于氮化硅层之上，所述步骤S2中形成的缓冲层凹槽属于氧化硅层。
所述缓冲层中氧化硅层的折射率为。
所述步骤S2中，通过干法蚀刻对所述对层间绝缘层、栅极绝缘层及缓冲层进行第一次蚀刻，进行所述第一次蚀刻所使用的蚀刻气体包含四氟化碳。
所述步骤S3中，通过干法蚀刻对所述缓冲层进行第二次蚀刻，进行所述第二次蚀刻所使用的蚀刻气体包含五氟乙烷。
所述步骤S4具体包括如下步骤：
步骤S41、依次沉积形成透明导电层和金属层，在所述金属层表面涂布形成光阻层，使用半色调光罩对光阻层进行曝光，进而对所述光阻层进行显影，得到光阻图案；
步骤S42、以光阻图案为遮蔽层，对所述透明导电层和金属层进行第一次蚀刻，由透明导电层和金属层分别得到重叠的透明导电图案和金属图案，所述金属图案包括目标金属图案和待离金属图案，所述透明导电图案包括分别对应于所述目标金属图案和待离金属图案下方的保留导电图案和目标导电图案，所述目标金属图案包括源漏极及触控线，所述目标导电图案包括像素电极；
步骤S43、通过灰化工艺，去掉所述待离金属图案上方所对应的光阻图案，对所述金属层进行第二次蚀刻，去掉所述待离金属图案，露出所述目标导电图案。
本发明还提供一种TFT基板，包括衬底基板、在衬底基板上的缓冲层、在缓冲层上的有源层、在缓冲层上覆盖有源层的栅极绝缘层、在栅极绝缘层上的栅极、在栅极绝缘层上覆盖栅极的层间绝缘层、在层间绝缘层上方的透明导电层及在透明导电层上的金属层；
所述有源层具有位于两端的源漏极接触区及位于中间的沟道区，所述有源层在两端的源漏极接触区上分别设有一接触区过孔；
所述层间绝缘层和栅极绝缘层上设有与接触区过孔连通的绝缘层过孔，所述缓冲层上设有与接触区过孔连通的缓冲层凹槽，且缓冲层凹槽和有源层之间在接触区过孔处形成底切结构；
所述透明导电层在接触区过孔处发生断裂，所述金属层连续伸入缓冲层凹槽内并填充缓冲层凹槽，所述金属层包括源漏极及触控线，所述源漏极通过缓冲层凹槽从下方与所述有源层的源漏极接触区相接触。
所述的TFT基板还包括设于衬底基板和缓冲层之间的遮光层、覆盖透明导电层和金属层的钝化层、设于所述钝化层上的公共电极层；
所述透明导电的材料为氧化铟锡；
所述有源层为低温多晶硅半导体层。
本发明的有益效果：本发明的TFT基板的制作方法，通过在有源层两端的源漏极接触区内分别设置接触区过孔，在缓冲层对应于所述接触区过孔下方形成缓冲层凹槽，并使缓冲层凹槽和有源层之间在接触区过孔处形成底切结构，从而使得透明导电层在接触区过孔处发生断裂，后续使得源漏极穿过绝缘层过孔和接触区过孔在缓冲层凹槽内从下方与有源层的源漏极接触区相接触，避开了7Mask技术中多晶硅与氧化铟锡接触而出现的肖特基接触势垒，使得源漏极从下方直接与有源层的源漏极接触区形成欧姆接触，提高了TFT器件的电子迁移率。本发明的TFT基板，有源层两端的源漏极接触区内分别设有接触区过孔，缓冲层对应于所述接触区过孔下方设有缓冲层凹槽，且缓冲层凹槽和有源层之间在接触区过孔处形成底切结构，使得透明导电层在接触区过孔处发生断裂，后续使得源漏极穿过绝缘层过孔和接触区过孔在缓冲层凹槽内从下方与有源层的源漏极接触区相接触，避开了7Mask技术中多晶硅与氧化铟锡接触而出现的肖特基接触势垒，使得源漏极从下方直接与有源层的源漏极接触区形成欧姆接触，提高了TFT器件的电子迁移率。
附图说明
为了能更进一步了解本发明的特征以及技术内容，请参阅以下有关本发明的详细说明与附图，然而附图仅提供参考与说明用，并非用来对本发明加以限制。
附图中，
图1为本发明的TFT基板的制作方法的流程示意图；
图2为本发明的TFT基板的制作方法的步骤S1的示意图；
图3为本发明的TFT基板的制作方法的步骤S1中所形成的有源层的平面示意图；
图4为本发明的TFT基板的制作方法的步骤S1中接触区过孔处的膜层结构示意图；
图5为本发明的TFT基板的制作方法的步骤S2的示意图；
图6为本发明的TFT基板的制作方法的步骤S2中接触区过孔处的膜层结构示意图；
图7为本发明的TFT基板的制作方法的步骤S3的示意图；
图8为本发明的TFT基板的制作方法的步骤S3中接触区过孔处的膜层结构示意图；
图9为本发明的TFT基板的制作方法的步骤S4的示意图；
图10为本发明的TFT基板的制作方法的步骤S4中透明导电层在接触区过孔处发生断裂的示意图；
图11为本发明的TFT基板的制作方法的步骤S4中源漏极在缓冲层凹槽内从下方接触有源层的示意图；
图12为本发明的TFT基板的制作方法的步骤S5的示意图暨本发明的TFT基板的结构示意图。
具体实施方式
为更进一步阐述本发明所采取的技术手段及其效果，以下结合本发明的优选实施例及其附图进行详细描述。
请参阅图1，本发明首先提供一种TFT基板的制作方法，包括如下步骤：
步骤S1、如图2所示，提供衬底基板10，并依次形成在衬底基板10上的遮光层15、在衬底基板10上覆盖遮光层15的缓冲层20、在缓冲层20上的有源层30、在缓冲层20上覆盖有源层30的栅极绝缘层40、在栅极绝缘层40上的栅极50、在栅极绝缘层40上覆盖栅极50的层间绝缘层60以及在层间绝缘层60上的平坦层70。
具体地，如图3-4所示，所述有源层30具有位于两端的源漏极接触区31及中间的位于两源漏极接触区31之间的沟道区32，所述有源层30在两端的源漏极接触区31上分别设有一接触区过孔35。
具体地，所述缓冲层20为氧化硅(SiOx)层和氮化硅(SiNx)层的组合，其中氧化硅层堆叠于氮化硅层之上。
具体地，所述栅极绝缘层40为氧化硅层；所述层间绝缘层60为氧化 硅层和氮化硅层的组合。
具体地，所述有源层30为低温多晶硅半导体层。
步骤S2、如图5所示，对所述平坦层70进行曝光、显影，在所述平坦层70上对应于所述接触区过孔35的上方形成光阻过孔75，以所述平坦层70为遮蔽层，对层间绝缘层60、栅极绝缘层40及缓冲层20进行第一次蚀刻，如图6所示，对应于所述接触区过孔35的上方在所述层间绝缘层60和栅极绝缘层40上形成与接触区过孔35及光阻过孔75连通的绝缘层过孔65，对应于所述接触区过孔35的下方在所述缓冲层20上形成与接触区过孔35连通的缓冲层凹槽25。
具体地，所述步骤S2中，通过干法蚀刻对所述对层间绝缘层60、栅极绝缘层40及缓冲层20进行第一次蚀刻，进行所述第一次蚀刻所使用的蚀刻气体包含四氟化碳(CF 4)。
具体地，所述步骤S2中形成的缓冲层凹槽25属于缓冲层20的氧化硅层
步骤S3、如图7所示，对所述缓冲层20进行第二次蚀刻，使得缓冲层20在缓冲层凹槽25处被横向蚀刻，如图8所示，使得缓冲层凹槽25的宽度增大，进而使缓冲层凹槽25和有源层30之间在接触区过孔35处形成底切(Under Cut)结构。
具体地，所述步骤S3中通过干法蚀刻对所述缓冲层20进行第二次蚀刻。
具体地，所述步骤S1中形成的缓冲层20的氧化硅层为疏松结构，其折射率为1.40-1.47，而正常结构的氧化硅层的折射率通常大于1.49，例如层间绝缘层60为氧化硅层；并且在所述步骤S3中进行所述第二次蚀刻所使用的蚀刻气体对缓冲层20具有选择蚀刻性，该蚀刻气体包含五氟乙烷，使得缓冲层20在缓冲层凹槽25处能够被横向蚀刻，进而使得缓冲层凹槽25和有源层30之间形成底切结构
步骤S4、如图9所示，在所述层间绝缘层60上方依次沉积形成透明导电层7和金属层8，如图10所示，所述透明导电层7在接触区过孔35处发生断裂，所述金属层8连续伸入缓冲层凹槽25内并填充缓冲层凹槽25，对所述透明导电层7和金属层8进行图案化处理，由金属层8形成源漏极81及触控线82，由透明导电层7形成像素电极71，如图11所示，所述源漏极81通过缓冲层凹槽25从下方与所述有源层30的源漏极接触区31相接触。
具体地，所述透明导电层7的材料为氧化铟锡。
需要解释的是，9mask技术中的层间绝缘层60和平坦层70的制备需要采用两道光罩工艺，但是在本发明的7mask技术中通过将平坦层70作为层间绝缘层60的光阻层使用，在步骤S3对层间绝缘层60进行图案化处理后，所述步骤S4在沉积形成所述透明导电层7和金属层8之前，将平坦层70剥离，仅通过一道光罩工艺便可以完成层间绝缘层70的制备，进而相对于9mask工艺节省了一道光罩制程；所述透明导电层7和金属层8形成在所述层间绝缘层60表面上。除此之外，所述步骤S4中也可以将平坦层70保留，所述透明导电层7和金属层8形成在所述平坦层70表面上。
具体地，所述步骤S4采用半色调光罩对所述透明导电层7和金属层8进行图案化处理，所述步骤S4具体包括如下步骤：
步骤S41、依次沉积形成透明导电层7和金属层8，在所述金属层8表面涂布形成光阻层，使用半色调光罩对光阻层进行曝光，进而对所述光阻层进行显影，得到光阻图案。
步骤S42、以光阻图案为遮蔽层，对所述透明导电层7和金属层8进行第一次蚀刻，由透明导电层7和金属层8分别得到重叠的透明导电图案和金属图案，所述金属图案包括目标金属图案和待离金属图案，所述透明导电图案包括分别对应于所述目标金属图案和待离金属图案下方的保留导电图案和目标导电图案，其中，所述目标金属图案包括源漏极81及触控线82，所述目标导电图案包括像素电极71，且所述待离金属图案上方的光阻图案的厚度小于目标金属图案上方的光阻图案的厚度。
步骤S43、通过灰化工艺，去掉所述待离金属图案上方所对应的光阻图案，对所述金属层8进行第二次蚀刻，去掉所述待离金属图案，露出所述目标导电图案。
步骤S5、如图12所示，在所述层间绝缘层60上形成覆盖透明导电层7和金属层8的钝化层90，在所述钝化层90上沉积并图案化形成公共电极层95。
本发明的TFT基板的制作方法，通过在有源层30两端的源漏极接触区31内分别设置接触区过孔35，在缓冲层20对应于所述接触区过孔35下方形成缓冲层凹槽25，并使缓冲层凹槽25和有源层30之间在接触区过孔35处形成底切结构，从而使得透明导电层7在接触区过孔35处发生断裂，后续使得源漏极81穿过绝缘层过孔65和接触区过孔35在缓冲层凹槽25内从下方与有源层30的源漏极接触区31相接触，避开了7Mask技术中多晶硅与氧化铟锡接触而出现的肖特基接触势垒，使得源漏极81从下方直接与有源层30的源漏极接触区31形成欧姆接触，提高了TFT器件的电子迁移 率。
基于上述的TFT基板的制作方法，本发明还提供一种TFT基板，包括衬底基板10、在衬底基板10上的遮光层15，在衬底基板10上覆盖遮光层15的缓冲层20、在缓冲层20上的有源层30、在缓冲层20上覆盖有源层30的栅极绝缘层40、在栅极绝缘层40上的栅极50、在栅极绝缘层40上覆盖栅极50的层间绝缘层60、在层间绝缘层60上方的透明导电层7、在透明导电层7上的金属层8、覆盖透明导电层7和金属层8的钝化层90及设于所述钝化层90上的公共电极层95；
所述有源层30具有位于两端的源漏极接触区31及位于中间的沟道区32，所述有源层30在两端的源漏极接触区31上分别设有一接触区过孔35；
在所述层间绝缘层60和栅极绝缘层40上设有与接触区过孔35连通的绝缘层过孔65，所述缓冲层20上设有与接触区过孔35连通的缓冲层凹槽25，且缓冲层凹槽25和有源层30之间在接触区过孔35处形成底切结构；
所述透明导电层7在接触区过孔35处发生断裂，所述透明导电层7包括像素电极71，所述金属层8连续伸入缓冲层凹槽25内并填充缓冲层凹槽25，所述金属层8包括源漏极81及触控线82，所述源漏极81通过缓冲层凹槽25从下方与所述有源层30的源漏极接触区31相接触。
具体地，所述透明导电层7的材料为氧化铟锡。
具体地，所述有源层30为低温多晶硅半导体层。
本发明的TFT基板，有源层30两端的源漏极接触区31内分别设有接触区过孔35，缓冲层20对应于所述接触区过孔35下方设有缓冲层凹槽25，且缓冲层凹槽25和有源层30之间在接触区过孔35处形成底切结构，使得透明导电层7在接触区过孔处35发生断裂，后续使得源漏极81穿过绝缘层过孔65和接触区过孔35在缓冲层凹槽25内从下方与有源层30的源漏极接触区31相接触，避开了7Mask技术中多晶硅与氧化铟锡接触而出现的肖特基接触势垒，使得源漏极81从下方直接与有源层30的源漏极接触区31形成欧姆接触，提高了TFT器件的电子迁移率。
综上所述，本发明的TFT基板的制作方法，通过在有源层两端的源漏极接触区内分别设置接触区过孔，在缓冲层对应于所述接触区过孔下方形成缓冲层凹槽，并使缓冲层凹槽和有源层之间在接触区过孔处形成底切结构，从而使得透明导电层在接触区过孔处发生断裂，后续使得源漏极穿过绝缘层过孔和接触区过孔在缓冲层凹槽内从下方与有源层的源漏极接触区相接触，避开了7Mask技术中多晶硅与氧化铟锡接触而出现的肖特基接触势垒，使得源漏极从下方直接与有源层的源漏极接触区形成欧姆接触，提 高了TFT器件的电子迁移率。本发明的TFT基板，有源层两端的源漏极接触区内分别设有接触区过孔，缓冲层对应于所述接触区过孔下方设有缓冲层凹槽，且缓冲层凹槽和有源层之间在接触区过孔处形成底切结构，使得透明导电层在接触区过孔处发生断裂，后续使得源漏极穿过绝缘层过孔和接触区过孔在缓冲层凹槽内从下方与有源层的源漏极接触区相接触，避开了7Mask技术中多晶硅与氧化铟锡接触而出现的肖特基接触势垒，使得源漏极从下方直接与有源层的源漏极接触区形成欧姆接触，提高了TFT器件的电子迁移率。
以上所述，对于本领域的普通技术人员来说，可以根据本发明的技术方案和技术构思作出其他各种相应的改变和变形，而所有这些改变和变形都应属于本发明后附的权利要求的保护范围。

Claims (10)

  1. 一种TFT基板的制作方法，包括如下步骤：
    步骤S1、提供衬底基板，并在衬底基板上形成由下至上依次设置的缓冲层、有源层、栅极绝缘层、层间绝缘层及平坦层；
    所述有源层具有位于两端的源漏极接触区及位于中间的沟道区，所述有源层在两端的源漏极接触区上分别设有一接触区过孔；
    步骤S2、在所述平坦层上对应于所述接触区过孔的上方图案化形成光阻过孔，以所述平坦层为遮蔽层，对层间绝缘层、栅极绝缘层及缓冲层进行第一次蚀刻，在所述层间绝缘层和栅极绝缘层上形成与接触区过孔连通的绝缘层过孔，在所述缓冲层上形成与接触区过孔连通的缓冲层凹槽；
    步骤S3、对所述缓冲层进行第二次蚀刻，使得缓冲层在缓冲层凹槽处被横向蚀刻，使缓冲层凹槽和有源层之间在接触区过孔处形成底切结构；
    步骤S4、在所述层间绝缘层上方依次沉积形成透明导电层和金属层，所述透明导电层在接触区过孔处发生断裂，所述金属层连续伸入缓冲层凹槽内并填充缓冲层凹槽，对所述透明导电层和金属层进行图案化处理，由金属层形成源漏极及触控线，由透明导电层形成像素电极，所述源漏极通过缓冲层凹槽从下方与所述有源层的源漏极接触区相接触。
  2. 如权利要求1所述的TFT基板的制作方法，还包括步骤S5、形成覆盖透明导电层和金属层的钝化层，在所述钝化层上沉积并图案化形成公共电极层。
  3. 如权利要求1所述的TFT基板的制作方法，其中，所述透明导电层的材料为氧化铟锡；
    所述有源层为低温多晶硅半导体层；
    所述步骤S1还包括在形成缓冲层之前，在衬底基板上形成遮光层。
  4. 如权利要求1所述的TFT基板的制作方法，其中，所述缓冲层为氧化硅层与氮化硅层的组合，其中氧化硅层堆叠于氮化硅层之上，所述步骤S2中形成的缓冲层凹槽属于氧化硅层。
  5. 如权利要求4所述的TFT基板的制作方法，其中，所述缓冲层中氧化硅层的折射率为1.40-1.47。
  6. 如权利要求1所述的TFT基板的制作方法，其中，所述步骤S2中，通过干法蚀刻对所述对层间绝缘层、栅极绝缘层及缓冲层进行第一次蚀刻，进行所述第一次蚀刻所使用的蚀刻气体包含四氟化碳。
  7. 如权利要求1所述的TFT基板的制作方法，其中，所述步骤S3中，通过干法蚀刻对所述缓冲层进行第二次蚀刻，进行所述第二次蚀刻所使用的蚀刻气体包含五氟乙烷。
  8. 如权利要求1所述的TFT基板的制作方法，其中，所述步骤S4具体包括如下步骤：
    步骤S41、依次沉积形成透明导电层和金属层，在所述金属层表面涂布形成光阻层，使用半色调光罩对光阻层进行曝光，进而对所述光阻层进行显影，得到光阻图案；
    步骤S42、以光阻图案为遮蔽层，对所述透明导电层和金属层进行第一次蚀刻，由透明导电层和金属层分别得到重叠的透明导电图案和金属图案，所述金属图案包括目标金属图案和待离金属图案，所述透明导电图案包括分别对应于所述目标金属图案和待离金属图案下方的保留导电图案和目标导电图案，所述目标金属图案包括源漏极及触控线，所述目标导电图案包括像素电极；
    步骤S43、通过灰化工艺，去掉所述待离金属图案上方所对应的光阻图案，对所述金属层进行第二次蚀刻，去掉所述待离金属图案，露出所述目标导电图案。
  9. 一种TFT基板，包括衬底基板、在衬底基板上的缓冲层、在缓冲层上的有源层、在缓冲层上覆盖有源层的栅极绝缘层、在栅极绝缘层上的栅极、在栅极绝缘层上覆盖栅极的层间绝缘层、在层间绝缘层上方的透明导电层及在透明导电层上的金属层；
    所述有源层具有位于两端的源漏极接触区及位于中间的沟道区，所述有源层在两端的源漏极接触区上分别设有一接触区过孔；
    在所述层间绝缘层和栅极绝缘层上设有与接触区过孔连通的绝缘层过孔，所述缓冲层上设有与接触区过孔连通的缓冲层凹槽，且缓冲层凹槽和有源层之间在接触区过孔处形成底切结构；
    所述透明导电层在接触区过孔处发生断裂，所述金属层连续伸入缓冲层凹槽内并填充缓冲层凹槽，所述金属层包括源漏极及触控线，所述源漏极通过缓冲层凹槽从下方与所述有源层的源漏极接触区相接触。
  10. 如权利要求9所述的TFT基板，还包括设于衬底基板和缓冲层之间的遮光层、覆盖透明导电层和金属层的钝化层、设于所述钝化层上的公共电极层；
    所述透明导电层的材料为氧化铟锡；
    所述有源层为低温多晶硅半导体层。
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