CN104505369B - Flexible TFT and its preparation technology for Flexible Displays back electrode - Google Patents

Abstract

The invention provides a flexible TFT used for flexible display back electrodes and its preparation process. On a flexible substrate, several units composed of gate, source and drain and filled with metal are fabricated and contacted with the source and drain. carbon nanotubes; then make an insulating layer pattern that completely covers the carbon nanotubes but not completely covers the source, drain and gate, and then prepares the gate jumper and the insulating layer film with through holes on it; made with conductive ink A conductive film that fills the through hole and contacts the drain electrode and is solidified; cuts the conductive film along the unit to form several pixel electrode units. The invention can replace the complex, expensive and time-consuming traditional flexible substrate preparation process, improve production efficiency and reduce production cost; the carbon nanotube layer is prepared by spray printing, does not require a high temperature working environment, and will not cause the flexible substrate to shrink and bend when heated.

Description

Flexible TFT for flexible display back electrode and its preparation process

technical field

The invention relates to a flexible TFT back plate and a manufacturing method thereof, in particular to a flexible TFT used for a flexible display back electrode and a manufacturing process thereof.

Background technique

The most common liquid crystal display is like the display panel of a calculator. Its image elements are directly driven by voltage. When controlling one unit, it will not affect other units. When the number of pixels increases to a large number such as millions, this This approach appears to be impractical. The problem does seem to be solved if the number of connecting wires can be reduced to thousands by arranging the pixels in rows and columns: all pixels in a column are driven by a positive potential, and all pixels in a row are driven by Driven by a negative potential, the pixel at the intersection of the row and the column will have the maximum voltage and be switched. However, this method still has a defect, that is, although other pixels in the same row or column receive only a partial voltage, this partial switching will still darken the pixel.

At present, the best solution is to add a transistor switch associated with each pixel, so that each pixel can be controlled independently. The meaning of the low leakage current characteristic of the transistor is that the voltage applied to the pixel will not be lost arbitrarily before the picture is refreshed. This kind of circuit layout is very similar to DRAM, except that the entire structure is not built on a silicon wafer, but on a substrate such as glass (Thin-Film Transistor, TFT).

Basically all TFT substrates are not resistant to high temperatures, so the TFT process must be carried out at a relatively low temperature. The silicon layer used is amorphous silicon or polysilicon layer produced by silicide gas. The development of contemporary display technology requires more High-performance TFT is used to drive LCD pixels and AMOLED pixels. Amorphous silicon TFT has the advantages of simple preparation process and good uniformity, but its mobility is low and cannot meet the requirements for driving; although low-temperature polysilicon has high migration, its Laser-assisted annealing is required and the manufacturing cost is too high, and the mass production uniformity of polysilicon is poor, which cannot meet the needs of large-area high-resolution display production.

Flexible display has the characteristics of thin, light and bendable, and can be used to manufacture display screens of display devices such as e-books and mobile phones. This type of display is soft and portable, has strong impact resistance, and can realize curly display; however, the current plastic substrate has poor surface flatness, and micron-scale bumps on the surface will cause device damage and poor reliability; The thermal expansion coefficients of the layers are different, and the growth and heat treatment of the film will cause bending and shrinkage, which is not conducive to the alignment of photolithography patterns, and is also not conducive to panel production.

Carbon Nanotube (CNT) is a tubular carbon molecule. According to the number of layers of the tube, it is divided into single-walled and multi-walled carbon nanotubes. The radial direction of the tube is very thin, only nanoscale, and in the axial direction It can be as long as tens to hundreds of microns. Due to its special structure, carbon nanotubes have some special electrical properties, and the internal structure of carbon nanotubes can be adjusted by changing the manufacturing process, so as to exhibit a single insulating, semiconducting or metallic property in a specific direction, and the electrical conductivity is controllable and Up to 10,000 times that of copper. CNT material has excellent mechanical properties, its hardness is equivalent to that of diamond, waterproof, and resistant to knocking and scratching; it has strong toughness and can immediately return to its original shape after being stretched and bent.

Contents of the invention

In view of the shortcomings of the prior art described above, the purpose of the present invention is to provide a flexible TFT for flexible display back electrodes and its preparation process, which is used to solve the problem of making carbon nanotube array graphics in the prior art. It makes the process complex and cumbersome, and solves the problem of high precision and low error tolerance in the prior art.

In order to achieve the above purpose and other related purposes, the present invention provides a flexible TFT preparation process for flexible display back electrodes. The preparation process at least includes: (1) providing a flexible substrate provided with a microstructure embossed pattern; The microstructure embossed pattern includes a number of units consisting of gates, sources and drains; the units are distributed in a matrix and each column of adjacent units in the matrix shares a gate, and each row of adjacent units shares a source , the source is located between the gate and the drain of the two adjacent units and extends out of the gate; and filling the groove formed by the embossed pattern with metal to form a conductive circuit; (2) making carbon nanotubes that are in contact with the source and drain of each unit and the channel region therebetween but do not completely cover the source and drain of the unit on the embossed pattern; (3) making an insulating layer pattern on the carbon nanotube; the insulating layer pattern completely covers the carbon nanotube; the insulating layer pattern is in contact with the source electrode, the drain electrode and the gate of each unit but not Completely cover the source, drain and gate of the unit; (4) prepare a horizontal T-shaped metal structure as a gate jumper; the arms of the T-shaped metal structure are located on the insulating layer pattern and are connected to each The gates of two adjacent units in the column are in contact; the projection of the main part of the T-shaped metal structure on the flexible substrate overlaps with the source and drain of each unit and its width does not exceed the insulating layer the width of the pattern; (5) on the gate jumper, make a layer of insulating layer film that covers the several units and has some through holes, and the several through holes are located on the drain of each unit (6) utilize conductive ink to make a layer of conductive film on the insulating layer film with through hole in described step (5); Conductive ink fills into described through hole and contacts and solidifies with described drain electrode; (7 ) cutting the conductive film along the unit to form several pixel electrode units.

Preferably, the method for forming the microstructure embossed pattern in the step (1) is to apply UV glue on the flexible substrate, and then use a special template and curing equipment to emboss the microstructure pattern on the UV glue .

Preferably, the method of filling the grooves formed by the embossed pattern with metal in the step (1) is electroplating, scratch printing or spray printing; the filled metal is copper or silver.

Preferably, the method for producing the carbon nanotubes in the step (2) is any one of spray printing, transfer or sputtering.

Preferably, the material of the carbon nanotubes in the step (2) has semiconductor properties.

Preferably, the method for making the pattern of the insulating layer in the step (3) is to make a polymer insulating layer on the carbon nanotubes by using jet printing technology.

Preferably, the process of making the gate jumper in the step (4) is jet printing technology.

Preferably, in the step (5), there is one through hole from the insulating film on the drain of each unit.

Preferably, the method for making the conductive film in the step (6) is screen printing technology or inkjet printing technology.

Preferably, the method for cutting the conductive film in the step (7) is laser cutting technology.

The present invention also provides a flexible TFT for a flexible display back electrode, the flexible TFT at least includes: a flexible substrate provided with a microstructure embossed pattern; A plurality of units composed of poles; carbon nanotubes located on the embossed pattern and in contact with the source and drain electrodes of each unit and the channel region therebetween; an insulating layer completely covering the carbon nanotubes pattern; the insulating layer pattern is in contact with the source, drain and gate of each unit; the T-shaped metal with double arms located on the insulating layer pattern and in contact with the gates of two adjacent units structure, the projection of the main part of the T-shaped metal structure on the flexible substrate overlaps with the source and drain of each unit; it is located on the T-shaped metal structure, covers the several units, and has several The insulating layer film of the through hole; the through hole is located above the drain of each unit; the conductive film that is filled in the through hole and is in contact with the drain and cured; the conductive film covers the An insulating layer film is separated from each other above and along each of the cells.

Preferably, the groove formed by the embossed pattern is filled with metal.

Preferably, the cells are distributed in a matrix, and adjacent cells in each column in the matrix share a gate, and adjacent cells in each row share a source.

Preferably, the source is located between the gate and drain constituting the two adjacent units and extends out of the gate.

Preferably, the carbon nanotubes cover the source and drain of each unit and part of the channel region therebetween.

Preferably, the insulating layer pattern covers part of the source, drain and gate of each unit.

Preferably, the double arms of the T-shaped metal structure are in contact with the gates of two adjacent cells in each row of cells.

Preferably, the T-shaped metal structure serves as a gate jumper.

Preferably, the width of the main part of the T-shaped metal structure does not exceed the width of the insulating layer pattern.

Preferably, the drain of each unit has a said via hole from said insulating film.

As mentioned above, the flexible TFT used for the flexible display back electrode of the present invention and its preparation process have the following beneficial effects: the embossing technology can utilize high-definition templates in UV glue (ultraviolet embossing) and thermosetting glue (hot embossing) Printing) and other flexible substrates to prepare micro-scale or even nano-scale microstructures, combined with conductive ink scraping technology or fine electroplating technology, can fill the microstructure with conductive metal to prepare ultra-fine conductive lines, and roll-to-roll imprinting technology The introduction makes it possible to produce large-scale batches of products at low cost; as traditional manufacturing processes, jet printing and silk printing are mature, with complete procedures and sound equipment. There is no extra R&D cost for introducing them into the flexible TFT manufacturing process, and they can replace complex and expensive consumption. The traditional TFT preparation process at that time improves production efficiency and reduces production costs; carbon nanotubes have excellent electrical and mechanical properties. By changing the structure of the carbon nanotube (CNT) itself, its electrical conductivity is changed to make it a semiconductor, and its mobility is higher than that of amorphous silicon and polycrystalline silicon. CNT itself has high hardness and strong toughness, and can be processed on various substrates, not limited to traditional substrates such as glass. In this patent, the CNT film layer is prepared by spray printing, which does not require a high-temperature working environment, and will not cause the flexible substrate to shrink and bend when heated.

Description of drawings

FIG. 1 is a schematic plan view of a flexible substrate with microstructure embossed patterns in the present invention.

Fig. 2 is a schematic plan view of the carbon nanotubes fabricated on the embossed pattern in the present invention, which are in contact with the source and drain electrodes and the channel region therebetween.

Fig. 3 is a schematic plan view of making an insulating layer pattern on carbon nanotubes in the present invention.

FIG. 4 is a schematic plan view of preparing a T-shaped gate jumper in the present invention.

FIG. 5 is a schematic plan view showing the planar structure of an insulating layer film with through holes formed on the gate jumper in the present invention.

Fig. 6 is a schematic plan view showing the plane structure of the conductive thin film fabricated on the insulating layer thin film in the present invention.

FIG. 7 is a schematic plan view of the planar structure of several pixel electrode units formed by cutting the conductive film along the units in the present invention.

Component designation description

10 flexible substrate

101 grid

102 source

103 drain

11 carbon nanotubes

12 Insulation graphics

13 Gate Jumper

14 insulating film

15 conductive film

detailed description

Embodiments of the present invention are described below through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific implementation modes, and various modifications or changes can be made to the details in this specification based on different viewpoints and applications without departing from the spirit of the present invention.

See Figures 1 through 7. It should be noted that the diagrams provided in this embodiment are only schematically illustrating the basic idea of the present invention, and only the components related to the present invention are shown in the diagrams rather than the number, shape and shape of the components in actual implementation. Dimensional drawing, the type, quantity and proportion of each component can be changed arbitrarily during actual implementation, and the component layout type may also be more complicated.

The flexible TFT preparation process for the flexible display back electrode of the present invention comprises the following steps:

Step 1: As shown in FIG. 1, FIG. 1 shows a schematic plan view of a flexible substrate with microstructure embossed patterns. Provide a flexible substrate 10 provided with a microstructure embossed pattern, the method for forming the imprinted pattern of the microstructure is preferably: coating UV glue on the flexible substrate, and then using a special template and curing equipment in the UV The microstructure pattern is embossed on the glue. The scale of the microstructure pattern in the present invention is micro-nano level. The microstructure embossed pattern includes several units composed of gate 101, source 102 and drain 103; the units are distributed in a matrix and each column of adjacent units in the matrix shares a gate, and each row of adjacent units share a source. The source is located between the gates forming the two adjacent cells and extends out of the matrix; as shown in Figure 1, Figure 1 provides a distribution of three rows and two columns; wherein gate 101 will drain The poles 103 are spaced apart, and the source 102 spans between the drains 103 and the gates 101 of two adjacent rows, wherein the drains 103 and the gates 101 of two adjacent rows share the source 102 with each other; one of the adjacent The gate, a source and a drain constitute a unit; that is to say, the source is shared with each other in the formed unit; since the final prepared source needs to be exposed, the source extends in the left and right direction of Figure 1 out of the grid. In this step, metal is filled in the groove formed by the embossed pattern to form a conductive circuit, wherein the method of filling the metal is preferably electroplating, scratch printing or spray printing; the metal filled in this embodiment is copper Or silver, the metal filled in the present invention also includes other metals except copper or silver.

Step 2: As shown in FIG. 2, FIG. 2 is a schematic plan view of the carbon nanotubes in contact with the source and drain electrodes fabricated on the embossed pattern. Fabricate carbon nanotubes 11 that are in contact with the source and drain of each unit and the channel region therebetween but do not completely cover the source and drain of the unit on the embossed pattern, that is to say The carbon nanotube 11 has an overlapping area with the source and drain of each unit, and there is one carbon nanotube 11 on the source and drain of each unit; as shown in Figure 2, each of the The carbon nanotubes on a unit do not completely overlap with the drain of the unit. Preferably, the method of covering the carbon nanotubes in the present invention includes any one of spray printing, transfer or sputtering. Carbon nanotube (CarbonNanotube, CNT) is a kind of tubular carbon molecule. According to the number of layers of the tube, it is divided into single-walled and multi-walled carbon nanotubes. The radial direction of the tube is very thin, only nanoscale, and in the axial direction. It can be as long as tens to hundreds of microns. Due to its special structure, carbon nanotubes have some special electrical properties, and the internal structure of carbon nanotubes can be adjusted by changing the manufacturing process, so as to exhibit a single insulating, semiconducting or metallic property in a specific direction, and the electrical conductivity is controllable and Up to ten thousand times that of copper. CNT material has excellent mechanical properties, its hardness is equivalent to that of diamond, waterproof, and resistant to knocking and scratching; it has strong toughness and can immediately return to its original shape after being stretched and bent. Preferably, the carbon nanotubes 11 in the present invention exhibit semiconductor properties.

Step 3: As shown in FIG. 3, FIG. 3 shows a schematic plan view of making insulating layer patterns on carbon nanotubes in the present invention. This step is to make an insulating layer pattern 12 on the carbon nanotube; the insulating layer pattern completely covers the carbon nanotube; the insulating layer pattern is in contact with the source, drain and gate of each unit but The source, drain and gate of the unit are not completely covered; and the insulating layer pattern is in contact with the channel region between the source, drain and gate of each unit. The black thick line frame in FIG. 3 represents the insulating layer pattern 12, and the insulating layer pattern 12 in FIG. 3 only schematically covers the source, drain and gate of the two columns on the left and middle. In this embodiment, preferably, the method for making the pattern of the insulating layer is to make a polymer insulating layer by jet printing technology.

Step 4: As shown in FIG. 4 , FIG. 4 is a schematic plan view of preparing a T-shaped gate jumper in the present invention. This step is to prepare a horizontal T-shaped metal structure as a gate jumper 13; the arms of the T-shaped metal structure are located on the insulating layer pattern 12 and are in contact with the gates of two adjacent cells in each column ; The projection of the main part of the T-shaped metal structure on the flexible substrate overlaps with the source and drain of each unit and its width does not exceed the width of the insulating layer pattern. The horizontal T-shaped metal structure means that the gate jumper 13 is horizontally positioned on the flexible substrate, that is, the arms of the T-shaped metal structure are placed on one side, and its vertical part (main part) Place on opposite side of both arms. As shown in Figure 4, the double arms of the T-shaped metal structure are located on the insulating layer pattern 12 and are in contact with the gates 101 of two adjacent cells in each row; the main part of the T-shaped metal structure ( The projection of the vertical part) on the flexible substrate overlaps the source and drain of each unit and its width does not exceed the width of the insulating layer pattern 12. That is, the main part (vertical part) of the T-shaped metal structure placed on each unit overlaps with the source and drain of the unit. The distance between the source and the drain in the unit is the width of the channel, and the main part of the T-shaped metal structure straddles the channel. Preferably, the process for making the gate jumper in this step is jet printing technology.

Step 5: As shown in FIG. 5 , FIG. 5 is a schematic plan view showing the planar structure of the insulating film with through holes formed on the gate jumper. This step is to make a layer of insulating layer film 14 covering the several units and having several through holes on the gate jumper, and the several through holes are located on the drain of each unit. Preferably, there is one said via hole from said insulating layer film above the drain of each cell. That is to say, each through hole on the insulating film 14 is aligned with the drain of a unit. And the entire insulating layer film covers the several units as a whole.

Step 6: As shown in FIG. 6, FIG. 6 shows a schematic plan view of a conductive film fabricated on an insulating film in the present invention. This step is to use conductive ink to make a layer of conductive film 15 on the insulating layer film with through holes in the step five; the conductive ink is filled into the through holes and is in contact with the drain electrode and cured; in Fig. 6 only It is shown that a conductive thin film covers the insulating layer thin film, while structures below the conductive thin film are not shown. Preferably, the method of making the conductive film is screen printing technology. Due to the existence of several small holes in the insulating layer film, the conductive ink fills the small holes and contacts the bottom exposed drain during silk printing, and the bottom exposed drain is connected to the outside after the conductive ink is cured.

Step 7: As shown in FIG. 7, FIG. 7 shows a schematic plan view of cutting the conductive film along the unit to form several pixel electrode units. The entire conductive film in FIG. 7 is cut along the unit to form several pixel electrode units. FIG. 7 only shows several pixel electrode units covered by the conductive thin film, and the structure below the conductive thin film of the several pixel electrode units is not shown. Preferably, in this step, the method of cutting the conductive film is laser cutting technology.

The present invention also provides a flexible TFT used for a flexible display back electrode, and the structural diagrams of various stages of forming the flexible TFT are shown in FIG. 1 to FIG. 7 . The flexible backplane at least includes: a flexible substrate provided with a microstructure embossed pattern; the microstructure embossed pattern includes several units composed of a gate, a source and a drain; preferably, the embossed pattern The formed trenches are filled with metal. The metal is copper or silver. Further preferably, the cells are distributed in a matrix, and adjacent cells in each column in the matrix share a gate, and adjacent cells in each row share a source. That is, all gates in each column that are spaced apart from each other by sources are eventually connected together, and the source below each drain in each row forms the common source for the transistors in that row. And the source is located between the gates and drains forming the two adjacent units and extends out of the gates. Carbon nanotubes located on the embossed pattern and in contact with the source and drain of each unit; preferably, the carbon nanotubes cover the source and drain of each unit and therebetween part of the channel region between them. That is to say, the carbon nanotubes do not completely cover the source and drain of each unit. The insulating layer pattern completely covering the carbon nanotubes; the insulating layer pattern is in contact with the source, drain and gate of each unit; preferably, the insulating layer pattern covers the each Portion of the source, drain, and gate of a cell. That is, the insulating layer pattern does not completely cover the source, drain and gate of each unit. A T-shaped metal structure with double arms located on the insulating layer pattern and in contact with the gates of two adjacent units. The projection of the main part of the T-shaped metal structure on the flexible substrate is consistent with the source and The drain overlaps; preferably, the width of the main part of the T-shaped metal structure does not exceed the width of the insulating layer pattern. An insulating layer film located on the T-shaped metal structure, covering the several units and having several through holes; the through holes are located on the drain of each unit; preferably, each of the The drain of the cell has said via hole from said insulating layer film. A conductive film that is filled in the through hole in contact with the drain electrode and solidified; the conductive film covers the insulating layer film and is separated from each other along each of the units.

The present invention utilizes micro-nano imprinting technology to prepare source, drain, and gate by scraping and curing conductive ink; the combined application of Imprinting, Ink-jetting, and Screen Printing bypasses the The high-precision and low-error-tolerance process necessary in the traditional process is eliminated; the application of carbon nanotube (CNT) material, due to its special adjustable electrical conductivity and low manufacturing difficulty, can replace amorphous in the preparation of specific products. Materials that exhibit semiconductor properties such as silicon and polysilicon.

In summary, the imprinting (Imprinting) technology of the present invention can use high-precision templates to prepare microstructures at the micron scale or even at the nanoscale on flexible substrates such as UV glue (ultraviolet imprinting) and thermosetting glue (hot embossing). , combined with conductive ink scraping technology or fine electroplating technology, can fill the microstructure with conductive metal to prepare ultra-fine conductive lines, and the introduction of roll-to-roll imprinting (R2R Imprinting) technology makes the large-scale mass production of products low-cost Possibly; Ink-jetting and Screen Printing are well-developed traditional manufacturing processes with complete procedures and sound equipment. There is no extra R&D cost to introduce them into the flexible TFT manufacturing process, and they can replace complex, expensive and time-consuming traditional TFT preparation process improves production efficiency and reduces production costs; carbon nanotubes have excellent electrical and mechanical properties. By changing the structure of CNT itself and changing its conductive properties, it becomes a semiconductor, and its mobility is higher than that of amorphous silicon and polycrystalline silicon. CNT itself has high hardness and strong toughness, and can be processed on various substrates, not limited to traditional substrates such as glass. In this patent, the CNT film layer is prepared by spray printing, which does not require a high-temperature working environment, and will not cause the flexible substrate to shrink and bend when heated. Therefore, the present invention effectively overcomes various shortcomings in the prior art and has high industrial application value.

The above-mentioned embodiments only illustrate the principles and effects of the present invention, but are not intended to limit the present invention. Anyone skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those skilled in the art without departing from the spirit and technical ideas disclosed in the present invention should still be covered by the claims of the present invention.

Claims (12)

1. A flexible TFT preparation process for flexible display back electrodes, characterized in that the preparation process at least includes: (1) providing a flexible substrate (10) provided with a microstructure embossed pattern; said microstructure embossed pattern includes several units consisting of a grid (101), a source (102) and a drain (103); The cells are distributed in a matrix, and each row of adjacent cells in the matrix shares a gate, and each row of adjacent cells shares a source, and the source is located between the gates and drains that make up the two adjacent cells. Extending out of the gate; and filling metal in the trench formed by the embossed pattern to form a conductive circuit; (2) above the embossed pattern, make the carbon nanotubes ( 11); (3) making an insulating layer pattern (12) on the carbon nanotube; the insulating layer pattern completely covers the carbon nanotube; The channel region in between contacts but does not completely cover the source, drain and gate of the cell; (4) Prepare a horizontal T-shaped metal structure as a gate jumper (13); the arms of the T-shaped metal structure are located on the insulating layer pattern and are in phase with the gates of two adjacent cells in each column Contact; the projection of the main part of the T-shaped metal structure on the flexible substrate overlaps with the source and drain of each unit and its width does not exceed the width of the insulating layer pattern; (5) making a layer of insulating layer film (14) covering the several units and having several through holes on the gate jumper, and the several through holes are located on the drain of each unit; (6) Utilize conductive ink to make a layer of conductive film (15) on the insulating layer film with through hole in described step (5); Conductive ink fills into described through hole and contacts with described drain electrode and solidifies; (7) Cutting the conductive film along the unit to form several pixel electrode units. 2. The flexible TFT manufacturing process for flexible display back electrodes according to claim 1, characterized in that: the method of forming the microstructure embossed pattern in the step (1) is to coat on the flexible substrate UV glue, and then use a special template and curing equipment to emboss microstructure graphics on the UV glue. 3. The flexible TFT manufacturing process for the flexible display back electrode according to claim 1, characterized in that: in the step (1), the method of filling the groove formed by the embossed pattern is to use Plating, scraping or spray printing; the metal to be filled is copper or silver. 4. The flexible TFT manufacturing process for flexible display back electrodes according to claim 1, characterized in that: the method of making the carbon nanotubes in the step (2) is spray printing, transfer or sputtering any kind. 5. A flexible TFT for a flexible display back electrode, characterized in that: the flexible TFT at least includes: A flexible substrate (10) provided with a microstructure embossed pattern; the microstructure imprinted pattern includes several units composed of a gate (101), a source (102) and a drain (103); carbon nanotubes located on the embossed pattern and in contact with the source and drain of each unit and the channel region therebetween; an insulating layer pattern completely covering the carbon nanotubes; the The insulating layer pattern is in contact with the source, drain and gate of each unit and the channel region therebetween; A T-shaped metal structure with double arms located on the insulating layer pattern and in contact with the gates of two adjacent units. The projection of the main part of the T-shaped metal structure on the flexible substrate is consistent with the source and The drains overlap; An insulating layer film located on the T-shaped metal structure, covering the several units and having several through holes; the through holes are located on the drain of each unit; filled between the through holes and the The conductive film that is in contact with the drain electrode and solidified; the conductive film is covered on the insulating layer film and separated from each other along each of the units; The cells are distributed in a matrix and each column of adjacent cells in the matrix shares a gate, and each row of adjacent cells shares a source; The trench formed by the embossed pattern is filled with metal. 6. The flexible TFT for flexible display back electrodes according to claim 5, wherein the source is located between the gate and the drain of the two adjacent units and extends out of the gate outside. 7. The flexible TFT for flexible display back electrodes according to claim 5, characterized in that: the carbon nanotubes cover the source and drain electrodes of each unit and the part of the channel region between them area. 8. The flexible TFT for flexible display back electrodes according to claim 5, characterized in that: the insulating layer pattern covers the source, drain and gate of each unit and the channel region therebetween part of the area. 9 . The flexible TFT for flexible display back electrodes according to claim 5 , wherein the double arms of the T-shaped metal structure are in contact with the gates of two adjacent cells in each row of cells. 10. The flexible TFT for flexible display back electrodes according to claim 9, wherein the T-shaped metal structure is used as a gate jumper. 11. The flexible TFT for flexible display back electrodes according to claim 9, wherein the width of the main part of the T-shaped metal structure does not exceed the width of the insulating layer pattern. 12. The flexible TFT used for the flexible display back electrode according to claim 5, characterized in that: the drain electrode of each unit has the through hole from the insulating film.