JP2001291871A - Flat-panel display and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flat panel-display with an improved driving ability of a TFT in a driving part and its manufacture. SOLUTION: At least 20 shots of laser beam of a rectangular shape with about 550 mJ/cm2 energy density is irradiated to an amorphous silicon thin film which is formed on a substrate, the amorphous silicon thin film is annealed to polycrystallize, and a TFT for the driving part is formed. Thus, the diameter of the polycrystalline silicon grain, which constitutes a TFT for the driving part, grows large enough, and the driving capacity of the TFT of the driving part gets improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flat panel display and a method of manufacturing the same, and more particularly, to a flat panel display with improved driving capability of a TFT of a driving unit and a method of manufacturing the same.

[0002]

2. Description of the Related Art In recent years, liquid crystal display panels have been widely used as display devices for various electronic devices. At present, as a liquid crystal display panel, switching elements formed in each pixel of a display unit are turned on / off.
An active matrix type that performs switching of pixels is mainly used.

In such an active matrix type liquid crystal display panel, in recent years, a film having a good film quality can be uniformly formed over a large area, and therefore, the pixel switching element is formed of an amorphous silicon thin film. TFTs are being used.

However, since amorphous silicon has low carrier mobility, there is a problem in that, when TFTs are manufactured using the amorphous silicon as it is, the current driving capability of the TFTs becomes extremely low. In particular, a TFT of a driving unit including a horizontal scanning circuit unit and a vertical scanning circuit unit is required to have a higher driving capability than a TFT for driving a pixel unit due to a demand for high-speed driving. In the case where the TFT for driving the pixel portion is formed on the same substrate, the driving capability of the TFT of the driving portion becomes largely insufficient if amorphous silicon is used.

Therefore, as a pixel switching element,
In a liquid crystal display panel using a TFT formed of an amorphous silicon thin film, each of a horizontal scanning circuit section and a vertical scanning circuit section is constituted by a dedicated IC, and these ICs are externally provided to the pixel section. It was common to connect.

However, in a liquid crystal display panel in which the horizontal scanning circuit section and the vertical scanning circuit section are configured by dedicated ICs and these ICs are connected to the pixel section from the outside, the manufacturing process becomes complicated, There was a problem that the cost was increased.

For this reason, a method of forming an amorphous silicon thin film on a substrate and then annealing the amorphous silicon thin film to crystallize silicon and improve the film quality has been proposed and widely used. As a method of such annealing, a method of irradiating an amorphous silicon thin film with a pulse laser in an ultraviolet wavelength range such as an excimer laser (laser annealing) is known.

As described above, by performing the annealing process, the amorphous silicon thin film is crystallized, and the mobility is increased. As a result, the driving capability of the TFT is increased, and high-speed operation becomes possible.

[0009]

In recent years, higher driving speeds have been demanded for a driving section including a horizontal scanning circuit section and a vertical scanning circuit section. At present, there is no liquid crystal display panel that can be answered.

[0010] In addition to the liquid crystal display panel, TF
A similar problem occurs in a flat panel display such as an EL display panel using T as a pixel switching element.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a flat panel display in which the driving capability of the TFT of the driving section is improved and suitable for high-speed operation, and a method of manufacturing the same.

[0012]

SUMMARY OF THE INVENTION The object of the present invention is as follows.
This is achieved by a flat panel display characterized in that the crystal grain size of the polycrystalline silicon constituting the TFT for the driving portion is larger than the channel length of the TFT.

According to the present invention, since the crystal grain size of the polycrystalline silicon constituting the TFT for the driving portion is larger than the channel length of the TFT, the driving portion has sufficient driving capability as a TFT and operates at high speed. It is possible to provide a flat panel display suitable for a computer.

In a preferred embodiment of the present invention, the polycrystalline silicon has a crystal grain size smaller than a channel width of the TFT.

In a further preferred aspect of the present invention, the polycrystalline silicon has a crystal grain size of 1 μm to 2 μm.
It is set to μm.

In a further preferred aspect of the present invention, the polycrystalline silicon comprises amorphous silicon,
Annealed by a rectangular laser beam,
Is formed.

In a further preferred aspect of the present invention, the polycrystalline silicon is formed by annealing the amorphous silicon by irradiating at least 20 shots of the rectangular laser beam.

In a further preferred embodiment of the present invention, the energy density of the rectangular laser beam is set to about 550 mJ / cm ² .

In a further preferred aspect of the present invention, the rectangular laser beam is constituted by an excimer laser beam.

In a further preferred aspect of the present invention, the excimer laser beam comprises a XeCl excimer laser beam, a KrF excimer laser beam, and an ArF excimer laser beam.
It is constituted by an excimer laser beam selected from the group consisting of excimer laser beams.

In a further preferred aspect of the present invention, the TFT has a channel length of about 1 μm.

In a further preferred aspect of the present invention, the TFT has a channel width of about 2 μm.

In a further preferred aspect of the present invention, the amorphous silicon is formed by a thin film formed on a substrate.

In a further preferred aspect of the present invention, the amorphous silicon thin film has a thickness of 70 nm.
It is formed as follows.

In a further preferred aspect of the present invention, the substrate is constituted by a substrate selected from the group consisting of a glass substrate and a plastic substrate.

The object of the present invention is also to irradiate the amorphous silicon with at least 20 shots of a rectangular laser beam having an energy density of about 550 mJ / cm ² to anneal the amorphous silicon to polycrystallize it. The present invention is achieved by a flat panel display in which a TFT for a driving unit is formed.

According to the present invention, the amorphous silicon is irradiated with at least 20 shots of a rectangular laser beam having an energy density of about 550 mJ / cm ² , and the amorphous silicon is annealed, polycrystallized, and driven. Since the TFTs for the driving section are formed, the crystal grain size of the polycrystalline silicon constituting the TFTs for the driving section is sufficiently large, and a flat panel display having a sufficient driving capability as the TFT for the driving section is provided.

In a preferred embodiment of the present invention, the rectangular laser beam is constituted by an excimer laser beam.

In a further preferred aspect of the present invention, the excimer laser beam comprises a XeCl excimer laser beam, a KrF excimer laser beam, and an ArF excimer laser beam.
It is constituted by an excimer laser beam selected from the group consisting of excimer laser beams.

In a further preferred aspect of the present invention, the TFT has a channel length of about 1 μm.

In a further preferred aspect of the present invention, the TFT has a channel width of about 2 μm.

In a further preferred aspect of the present invention, the amorphous silicon is formed by a thin film formed on a substrate.

In a further preferred aspect of the present invention, the amorphous silicon thin film has a thickness of 70 nm.
It is formed as follows.

In a further preferred aspect of the present invention, the substrate is constituted by a substrate selected from the group consisting of a glass substrate and a plastic substrate.

The object of the present invention is also to provide an amorphous silicon thin film formed on a substrate with a thickness of about 550 mJ / cm.
2 a rectangular laser beam having a ^second energy density
This is achieved by a method for manufacturing a flat panel display, which comprises irradiating 0 or more shots, annealing the amorphous silicon thin film, polycrystallizing it, and forming a TFT for a driving section.

According to the present invention, the amorphous silicon thin film formed on the substrate is irradiated with at least 20 shots of a rectangular laser beam having an energy density of about 550 mJ / cm ² to anneal the amorphous silicon thin film. Then, since the TFT for the driving unit is formed by polycrystallization, the crystal grain size of the polycrystalline silicon constituting the TFT for the driving unit becomes sufficiently large, and the TF of the driving unit becomes large.
It is possible to obtain a flat panel display having a sufficient driving capability as T.

In a preferred embodiment of the present invention, the rectangular laser beam is constituted by an excimer laser beam.

In a further preferred aspect of the present invention, the excimer laser beam is a XeCl excimer laser beam, a KrF excimer laser beam, or an ArF excimer laser beam.
It is constituted by an excimer laser beam selected from the group consisting of excimer laser beams.

In a further preferred aspect of the present invention, the channel length of the TFT is set to about 1 μm.

In a further preferred embodiment of the present invention, the channel width of the TFT is set to about 2 μm.

In a further preferred aspect of the present invention, the amorphous silicon thin film has a thickness of 70 nm.
It is formed as follows.

In a further preferred aspect of the present invention, the substrate is constituted by a substrate selected from the group consisting of a glass substrate and a plastic substrate.

[0043]

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

First, the principle that amorphous silicon is crystallized by annealing will be described with reference to FIG.

FIG. 1 shows that an XeCl excimer laser having a resonance wavelength of 308 nm
It is a graph which shows the temperature change at the time of irradiation for nsec.

As shown in FIG. 1, when the excimer laser is irradiated on the amorphous silicon thin film, the temperature of the amorphous silicon thin film starts to rise and reaches about 1100 ° C.
Then, the amorphous silicon thin film starts to melt. At this time, the temperature of the amorphous silicon thin film is substantially about 11
The temperature remains at 00 ° C. When the amorphous silicon thin film is completely melted, the temperature of the amorphous silicon thin film rises again. At this point, when the irradiation of the excimer laser is stopped, the cooling of the amorphous silicon thin film is started. When the temperature of the thin film reaches about 1420 ° C. by cooling, silicon crystals begin to grow. At this time, the temperature of the amorphous silicon thin film changes substantially at about 1420 ° C. Once the amorphous silicon has completely solidified,
The temperature drops.

Through such a process, the crystallization of the amorphous silicon thin film progresses, and by repeatedly performing the crystallization a plurality of times, a polycrystalline silicon film having a desired grain size can be obtained.

FIG. 2 is a schematic perspective view of a laser annealing apparatus according to a preferred embodiment of the present invention.

As shown in FIG. 2, the laser annealing apparatus 1 has a laser oscillator 11 for generating a XeCl excimer laser beam 21 having a resonance wavelength of 308 nm. In this embodiment, the laser oscillator 11 is configured to generate a rectangular XeCl excimer laser beam 21. Xe emitted from the laser oscillator 11
A reflecting mirror 31 is provided on the optical path of the Cl excimer laser beam 21.
Is provided, and a XeCl excimer laser beam 21 is provided.
Is reflected by the reflecting mirror 31 and guided to the attenuator 12.

In the optical path of the XeCl excimer laser beam 21 having passed through the attenuator 12, a reflecting mirror 32 is provided. The XeCl excimer laser beam 21 is reflected by the reflecting mirror 32 and scans the XeCl excimer laser beam 21 in the x direction. The laser beam enters the reflecting mirror 33 attached to the laser scanning mechanism 39 and is scanned in the x direction. The reflecting mirror 32 is attached to a laser scanning mechanism 40 that scans the XeCl excimer laser beam 21 in the y direction.

In the optical path of the XeCl excimer laser beam 21 reflected by the reflecting mirror 33, a reflecting mirror 34 is provided. The XeCl excimer laser beam 21 is reflected by the reflecting mirror 34 and guided to the beam homogenizer 14. The beam homogenizer 14 of the XeCl excimer laser beam 21 makes the laser high intensity in the radial direction of the light beam substantially uniform.

XeC passing through the beam homogenizer 14
In the optical path of the excimer laser beam 21, the chamber 1
5 are arranged. Inside the chamber 15, a stage 16 on which a glass substrate 91 having an amorphous silicon thin film (not shown) formed on the surface is mounted. In addition, a transmission window 41 formed of quartz glass that transmits the XeCl excimer laser beam 21 is provided in an upper part of the chamber 15.

The XeCl excimer laser beam 21 that has entered the chamber 15 is converted into an amorphous silicon thin film (not shown) formed on a glass substrate 91 by a laser scanning mechanism 39 and a laser scanning mechanism 40 in the x-axis direction and the y-axis direction. The XeCl excimer laser beam 21 is irradiated on the entire surface of the amorphous silicon thin film formed on the glass substrate 91.

The laser annealing apparatus according to a preferred embodiment of the present invention having the above-described configuration anneals an amorphous silicon film formed on a glass substrate 91 to polycrystallize it as follows. Then, the TFT of the driving unit of the liquid crystal display panel is generated.

About 550 mJ / c from the laser oscillator 11
A rectangular XeCl excimer laser beam 21 having an energy density of m ² is emitted, and the XeCl excimer laser beam 21 is guided into the chamber 15 by an optical system.

The XeCl excimer laser beam 21 is emitted by a laser scanning mechanism 39 and a laser scanning mechanism 40.
The amorphous silicon thin film formed on the glass substrate 91 is scanned in the x-axis direction and the y-axis direction, and the entire surface of the amorphous silicon thin film is irradiated with the XeCl excimer laser beam 21.

In this embodiment, a rectangular XeCl
The excimer laser beam 21 has a continuous irradiation area by a laser scanning mechanism 39 and a laser scanning mechanism 40.
The amorphous silicon thin film is moved stepwise in the x-axis direction and the y-axis direction so as to overlap in a certain range, and each region of the amorphous silicon thin film is irradiated with the XeCl excimer laser beam 21 of 20 shots or less. It is configured to receive irradiation.

In the present embodiment, the driving unit TFT of the liquid crystal display panel has a more sufficient driving capability,
The amorphous silicon film is annealed by the XeCl excimer laser beam 21 so that the crystal grain size of the polycrystalline silicon of the TFT for the driving unit is larger than the channel length of the TFT so as to be suitable for high-speed operation. Be transformed into

Preferably, the crystal grain size of the polycrystalline silicon of the driving unit TFT is larger than the channel length of the TFT,
At the same time, the amorphous silicon film is annealed by the XeCl excimer laser beam 21 so as to be smaller than the channel width of the TFT to be polycrystallized.

In this embodiment, the TFT for the driving section of the liquid crystal display panel has a channel length of about 1 μm and a channel width of about 2 μm.

[0061]

EXAMPLES Examples will be given below to further clarify the effects of the present invention.

An amorphous silicon thin film having a thickness of 40 nm was formed on a glass substrate, and the amorphous silicon thin film was obtained by annealing using a laser annealing apparatus shown in FIG. 2 while changing the number of shots. The crystal grain size of the polycrystalline silicon was measured.

Here, the laser beam is 550 m
A XeCl excimer laser beam having an energy density of J / cm ² was used, and the pulse width was ５ Hz.

FIG. 3 shows the measurement results.

As shown in FIG. 3, the crystal grain size of the obtained polycrystalline silicon increases as the number of shots irradiated with the XeCl excimer laser beam increases up to 20 shots. Diameter is about 150
0 nm (1.5 μm). On the other hand, if it exceeds 20 shots, the crystal grain size of the polycrystalline silicon does not increase any more, and the effect of increasing the crystal grain size of the polycrystalline silicon is as follows.
Saturation was observed at 20 shots. Therefore, it has been found that it is desirable to irradiate at least 20 shots of a XeCl excimer laser beam in order to make the driving unit TFT of the liquid crystal display panel have sufficient driving capability and be suitable for high-speed operation.

TF for driving section of liquid crystal display panel
The channel length and channel width of T are each about 1 μm.
m and about 2 μm, from FIG. 3, by irradiating at least 20 shots of a XeCl excimer laser beam, the crystal grain size of silicon constituting the TFT for the driving unit is larger than the channel length of the TFT, and ,
It was found to be smaller than the channel width.

The present invention is not limited to the above-described embodiments and examples, and various modifications can be made within the scope of the invention described in the claims, which are also included in the scope of the present invention. It goes without saying that it is included.

For example, in the above embodiment, the TFT for the drive unit of the liquid crystal display panel is generated, but the present invention is not limited to the TFT for the drive unit of the liquid crystal display panel. The present invention can be widely applied to the generation of a TFT for a driving portion of a flat display panel, such as a TFT for a flat display panel.

In the above embodiment, the XeCl excimer laser beam 21 having a resonance wavelength of 308 nm is used.
8 nm), ArF excimer laser beam (resonance wavelength 19
(3 nm) Another excimer laser beam such as an excimer laser beam may be used. The laser beam is not limited to the excimer laser beam, and another laser beam, or an energy beam such as an electron beam or an infrared beam may be used.

Further, in the above embodiment, an amorphous silicon thin film having a thickness of 40 nm is formed on a glass substrate, and an annealing process is performed using a XeCl excimer laser beam. Is not limited to 40 nm, and preferably 70 nm or less.

In the above embodiment, the amorphous silicon thin film is formed on the glass substrate 91. However, instead of the glass substrate 91, the amorphous silicon thin film is formed on another substrate such as a plastic substrate. You may.

Further, in the above embodiment, the laser annealing treatment apparatus 1 shown in FIG. 2 is used to irradiate the XeCl excimer laser beam 21 to the amorphous silicon thin film, but the present invention is not limited to this. Instead, another laser annealing apparatus can be used. For example, in the laser annealing apparatus 1 shown in FIG. 2, the XeCl excimer laser 21 is scanned stepwise in the x-axis direction and the y-axis direction by the laser scanning mechanisms 39 and 40. With the optical path fixed, the stage 16
The amorphous silicon thin film may be scanned by moving in the direction and the y direction.

In the above embodiment, XeCl
Although the amorphous silicon thin film is scanned stepwise by the excimer laser beam 21, the XeCl excimer laser 21 can be collectively irradiated on the entire surface of the amorphous silicon thin film even when the amorphous silicon thin film is continuously scanned. .

Further, in the above embodiment, the rectangular XeCl excimer laser beam 21 is applied to the glass substrate 9.
1, the XeCl excimer laser beam 21 is not limited to a rectangular shape, but may be a circular or linear XeC excimer laser beam.
An excimer laser beam 21 may be used.

[0075]

According to the present invention, it is possible to provide a flat panel display suitable for high-speed operation and a method of manufacturing the same, in which the driving capability of the TFT of the driving section is improved.

[Brief description of the drawings]

FIG. 1 shows an amorphous silicon thin film with XeCl
It is a graph which shows the temperature change at the time of excimer laser irradiation for 160 nsec.

FIG. 2 is an overall view showing a laser annealing treatment apparatus for irradiating an amorphous silicon thin film with a XeCl excimer laser to perform crystallization.

FIG. 3 is a graph showing the relationship between the number of shots (irradiation times) of a XeCl excimer laser having an energy density of 550 mJ / cm ² and the crystal grain size of an amorphous silicon thin film.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Annealing apparatus 11 Laser oscillator 12 Attenuator 14 Beam homogenizer 15 Chamber 16 Stage 21 XeCl excimer laser 31-34 Reflection mirror 39, 40 Laser scanning mechanism 41 Transmission window 91 Glass substrate

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification FI FI Theme Court II (Reference) H01L 29/78 627G (72) Inventor Hideharu Nakajima 6-7-35 Kita Shinagawa, Shinagawa-ku, Tokyo Sony Stock In-company F-term (reference) 2H092 JA24 JA31 JA32 KA04 KA05 MA30 NA21 PA01 5C094 AA21 BA03 BA43 CA19 DA13 EB02 5F052 AA02 AA03 AA06 BA18 BA20 BB07 DA02 JA01 5F110 AA01 BB02 DD01 DD02 GG02 PP03 GG16 PP03 PP25

Claims (28)

[Claims] 1. A flat panel display, wherein a crystal grain size of polycrystalline silicon constituting a TFT for a driving portion is larger than a channel length of the TFT. 2. The flat panel display according to claim 1, wherein a crystal grain size of said polycrystalline silicon is smaller than a channel width of said TFT. 3. The polycrystalline silicon has a crystal grain size of 1 μm.
The flat panel display according to claim 1, wherein the flat panel display is formed to have a thickness of m to 2 μm. 4. The flat according to claim 1, wherein the polycrystalline silicon is formed by annealing amorphous silicon with a rectangular laser beam. Panel display. 5. The polycrystalline silicon according to claim 4, wherein the amorphous silicon is formed by annealing the amorphous silicon by irradiating at least 20 shots of the rectangular laser beam. Flat panel display. 6. The flat panel display according to claim 4, wherein the energy density of the rectangular laser beam is set to about 550 mJ / cm ² . 7. The flat panel display according to claim 4, wherein said rectangular laser beam is constituted by an excimer laser beam. 8. An excimer laser beam, comprising: XeCl
8. The flat panel display according to claim 7, comprising an excimer laser beam selected from the group consisting of an excimer laser beam, a KrF excimer laser beam, and an ArF excimer laser beam. 9. The flat panel display according to claim 1, wherein the TFT has a channel length of about 1 μm. 10. The TFT has a channel width of about 2 μm.
The flat panel display according to claim 1, wherein the flat panel display is formed. 11. The flat panel display according to claim 4, wherein the amorphous silicon is formed by a thin film formed on a substrate. 12. The flat panel display according to claim 11, wherein said amorphous silicon thin film has a thickness of 70 nm or less. 13. The flat panel display according to claim 11, wherein the substrate is constituted by a substrate selected from the group consisting of a glass substrate and a plastic substrate. 14. 550 m of amorphous silicon
A flat-shaped TFT is formed by irradiating at least 20 shots of a rectangular laser beam having an energy density of J / cm ² , annealing the amorphous silicon, and polycrystallizing the amorphous silicon to form a TFT for a driving portion. Panel display. 15. The flat panel display according to claim 14, wherein the rectangular laser beam is constituted by an excimer laser beam. 16. The excimer laser beam may be XeC
16. The flat panel display according to claim 15, comprising an excimer laser beam selected from the group consisting of 1 excimer laser beam, KrF excimer laser beam, and ArF excimer laser beam. 17. The TFT according to claim 1, wherein a channel length of the TFT is about 1 μm.
The flat panel display according to any one of claims 14 to 16, wherein the flat panel display is formed. 18. A channel width of the TFT is about 2 μm.
The flat panel display according to any one of claims 14 to 17, wherein the flat panel display is formed. 19. The flat panel display according to claim 14, wherein the amorphous silicon is formed by a thin film formed on a substrate. 20. The flat panel display according to claim 19, wherein the amorphous silicon thin film has a thickness of 70 nm or less. 21. The flat panel display according to claim 19, wherein the substrate is constituted by a substrate selected from the group consisting of a glass substrate and a plastic substrate. 22. An amorphous silicon thin film formed on a substrate is irradiated with at least 20 shots of a rectangular laser beam having an energy density of about 550 mJ / cm ² , and the amorphous silicon thin film is annealed. A method for manufacturing a flat panel display, which comprises crystallizing to form a TFT for a driving portion. 23. The method according to claim 22, wherein the rectangular laser beam is constituted by an excimer laser beam. 24. The excimer laser beam is XeC
24. The method for manufacturing a flat panel display according to claim 23, comprising an excimer laser beam selected from the group consisting of an excimer laser beam, a KrF excimer laser beam, and an ArF excimer laser beam. 25. The method according to claim 22, wherein the TFT has a channel length of about 1 μm. 26. The method according to claim 22, wherein the TFT has a channel width of about 2 μm. 27. The method of manufacturing a flat panel display according to claim 22, wherein the thickness of the amorphous silicon thin film is formed to be 70 nm or less. 28. The method for manufacturing a flat panel display according to claim 22, wherein the substrate is constituted by a substrate selected from the group consisting of a glass substrate and a plastic substrate. .