JP2003273119A - Thin-film transistor and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method for enabling the upsizing of a substrate and low-cost manufacturing, and a TFT obtained thereby. <P>SOLUTION: The method for manufacturing a thin-film transistor comprises steps of coating a silicon grain layer on the substrate and irradiating the silicon grain with a laser beam. The coating is preferably carried out by printing or an ink jet. A part or the whole of the silicon grain layer is poly-siliconized or can be operated as a channel of the TFT by securing conductivity. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a manufacturing method for manufacturing a thin film transistor (hereinafter referred to as TFT) without using a vacuum process and a TFT obtained by the manufacturing method.

[0002]

2. Description of the Related Art FIG. 7 is a sectional view showing a conventional polysilicon film. In FIG. 7, 1 is a glass substrate, 14 is an oxide film (SiO ₂ ), 15 is a hydrogen-containing amorphous silicon film, 17 is an excimer laser, and 16 is a polysilicon film.

Next, the operation will be described. A hydrogen-containing amorphous silicon film 15 is formed on the oxide film 14 of the substrate 1.
Is deposited, heat treatment for dehydrogenation treatment is performed, and an excimer laser 17 is irradiated to perform annealing treatment (FIG. 7).
(A)). By the annealing treatment, the amorphous silicon is melted, and when it is solidified, it is recrystallized and changed into the polysilicon film 16 (FIG. 7B). This polysilicon film can be operated as a TFT channel.

[0004]

Conventional polysilicon T
In FT, since a hydrogen-containing amorphous silicon film is formed by a CVD method or the like, a film forming apparatus having a chamber for forming a film by a vacuum process is necessary. The substrate to be used is limited by the size of the chamber of the film forming apparatus, and there is a limit to the size increase of the substrate. Further, there is a drawback that the film forming process requires a long time and the cost becomes high.

The present invention has been made in order to solve the above-mentioned problems, and after applying silicon particles, a channel film of a TFT is formed by laser irradiation and a chamber such as a vacuum chamber is not used. The present invention relates to a manufacturing method for forming a TFT by a process. Since a vacuum process is not used, the substrate can be made large, and the time required for coating is short, so that it is an object of the present invention to provide a manufacturing method and a TFT obtained by which the manufacturing cost can be kept low. is there.

[0006]

Printing T according to the present invention
In FT, a silicon particle layer is formed by coating,
The laser irradiation raises the surface temperature of the silicon particles to melt them and recrystallize them, so that conduction between the particles can be secured. Since each silicon particle is a single crystal or polysilicon particle, it has high mobility, and since the particle interfaces are joined to ensure conduction, the silicon particle layer should form a high mobility channel film. You can

That is, the first manufacturing method of the present invention is a method of manufacturing a thin film transistor, which comprises the steps of applying silicon particles onto a substrate and irradiating the silicon particles with a laser.

A second manufacturing method of the present invention is the method of manufacturing a thin film transistor according to the first manufacturing method, wherein the coating is performed by printing.

A third manufacturing method of the present invention is the method of manufacturing a thin film transistor according to the first manufacturing method, wherein the coating is performed by ink jet.

A fourth manufacturing method of the present invention is the method of manufacturing a thin film transistor according to the first, second or third manufacturing method, in which a part or all of the silicon particle layer is poly-siliconized by the laser irradiation.

A fifth manufacturing method of the present invention is the method of manufacturing a thin film transistor according to the first, second or third manufacturing method, wherein the conduction of the silicon particle layer is secured by the laser irradiation.

The sixth manufacturing method of the present invention comprises the first, second,
The manufacturing method of 3, 4 or 5 is the manufacturing method of a thin film transistor, wherein the silicon particles are single crystal silicon particles.

The seventh manufacturing method of the present invention comprises the first, second,
The manufacturing method of 3, 4 or 5 is the method of manufacturing a thin film transistor, wherein the silicon particles are polysilicon particles.

The eighth manufacturing method of the present invention comprises the first, second,
The method of manufacturing a thin film transistor according to any one of 3, 4, 5, 6 or 7, including a step of applying silicon oxide particles having a surface covered with silicon oxide onto the substrate.

The ninth manufacturing method of the present invention comprises the first, second,
3, 4, 5, 6, 7, or 8, a method of manufacturing a thin film transistor, which includes the steps of forming an electrode on a substrate, applying donor-doped silicon particles, and irradiating the silicon particles with a laser. Is.

The tenth manufacturing method of the present invention is the first, second,
3, 4, 5, 6, 7, or 8, a method of manufacturing a thin film transistor, which includes a step of forming an electrode on a substrate, a step of applying acceptor-doped silicon particles, and a step of irradiating the silicon particles with a laser. Is.

The first thin film transistor of the present invention is a thin film transistor obtained by the first, second, third, fourth, fifth, sixth, seventh, eighth, ninth or tenth manufacturing method.

[0018]

Embodiment 1 FIG. 1 is a diagram for explaining channel formation of a TFT according to one embodiment of the present invention.

In FIG. 1A, 1 is a substrate and 2 is a silicon particle layer formed by printing. The silicon particle layer can be obtained by applying solution-type silicon particles obtained by mixing butyl carbitol as a vehicle and ethyl cellulose as a binder using a flexographic printing machine. Then, butyl carbitol is scattered and evaporated by drying, and ethyl cellulose is oxidized and scattered by baking, and a silicon particle layer is formed. In addition, as a method of applying the silicon particles other than the printing, an inkjet method, a spray method, a spin coating method, etc. may be mentioned. Of these, the printing method is preferable. Examples of the printing method include flexographic printing and screen printing. Of these, the flexographic printing method is preferable. At this time,
The silicon particles to be applied are preferably used in the form of a solution by mixing with a vehicle, a binder or the like.

The thickness of the silicon particle layer formed is 10
It is preferably ˜500 nm. If the thickness is less than 10 nm, it is difficult to form a uniform film thickness, and it tends to be difficult to secure a conduction path as a TFT channel. Further, if it exceeds 500 nm, the number of defects tends to increase, and more laser power tends to be required during laser annealing.

Then, a laser 1 is applied to the silicon particle layer 2.
By performing the irradiation of 7, the temperature of the surface of the silicon particles located above the silicon particle layer 2 rises and the surface melts (FIG. 1 (b)). When the surfaces of the silicon particles are melted, adjacent particle interface portions are joined and integrated. When the laser irradiation is stopped, the temperature drops and it solidifies. Upon solidification, adjacent silicon particle interface portions are bonded together in a bonded state to form the channel layer 3. Since the silicon particles are formed of single crystal or polysilicon and form a silicon film (channel layer 3) in which particle interfaces are integrated with each other, the channel layer 3 ensures conduction.
It can be operated as a channel of FT (Fig. 1
(C)). Since the channel layer 3 can secure high mobility, the TFT operation can be realized by controlling the current flowing through the channel layer 3. The silicon particle layer where the interface is not bonded and integrated does not work as a channel,
It also serves as a layer that prevents impurities from entering from the substrate. The silicon particle layer 2 may be formed by printing or inkjet. As the silicon particles, single crystal silicon particles or polysilicon particles may be used.

Embodiment 2 In FIG. 2A, 1 is a substrate and 2 is a silicon particle layer. Irradiate the silicon particle layer with a laser as shown in FIG. 2B (enlarge the laser power as compared with FIG. 1).
And the whole silicon particle is melted. When the laser irradiation is stopped, the molten silicon particles are solidified, but at this time, the silicon particles are recrystallized to form the polysilicon layer 4. The polysilicon layer 4 can be operated as a channel of the TFT. The non-recrystallized silicon particle layer serves as a layer that prevents impurities from entering from the substrate.

Embodiment 3 In FIG. 3A, reference numeral 1 is a substrate, and 5 is a silicon oxide particle layer whose particle surface is covered with an oxide film. The irradiation of the laser 17 is performed after the silicon particles are coated on the silicon oxide particle layer 5 to form the silicon particle layer 2 (FIG. 3).
(B)). When the surface of the silicon particle layer 2 is melted by laser irradiation and is solidified, the interface is joined and the silicon particles are conducted to form the channel layer 3 of the TFT (FIG. 3).
(C)). The layer 5 made of silicon oxide in which the surfaces of the silicon particles are covered with an oxide film prevents impurities from entering the substrate.

Although the surface of the silicon particles is melted in the figure, the entire silicon particles may be melted and recrystallized to form a polysilicon film.

Fourth Embodiment In FIG. 4A, 1 is a substrate, 6 is a drain electrode, and 7
Is a source electrode. After forming the source electrode 7 and the drain electrode 6, a donor-doped silicon particle layer is applied. When the silicon particle layer is irradiated with laser, the surface of the silicon particle is melted, and when the laser irradiation is stopped, the melted silicon surface is solidified to form ohmic contact layers 8 and 9 for the source electrode and the drain electrode. Next, FIG.
In (b), the silicon particle layer 10 in which the surfaces of the silicon particles are covered with an oxide film is applied to form an insulating film. Next, in FIG. 4C, the silicon particle layer 2 is applied,
Laser irradiation is performed later. The laser irradiation melts the surface of the silicon particles. When the laser irradiation is stopped, the temperature lowers and solidifies, and adjacent silicon particles become conductive. Figure 4 (d)
As shown in FIG. 3, the silicon particle layers (channel layers) 3 are bonded to each other in a state where the adjacent silicon particle interface portions are bonded. As shown in FIG. 4E, a silicon oxide film 11 is formed by coating, and finally a gate electrode 12 is formed. Thereby, an n-channel TFT can be formed. Figure 4
In the above, the contact-layers 8 and 9 with the electrodes were formed by using donor-doped silicon particles, but acceptor-doped silicon particles may be used, and in this case, a p-channel TFT can be formed. In FIG. 4, a TFT having a top gate structure in which the gate electrode is at the top
However, a TFT having an undergate structure in which the gate electrode is located at the bottom as shown in FIG. 5 may be used.

FIG. 6 shows a structure in which a recess is formed in the substrate 1, the thickness of the insulating layer is increased, and the intrusion of impurities from the substrate is further suppressed.

[0027]

According to the first manufacturing method of the present invention, TF
Since the channel layer of T is formed by coating and laser irradiation, it can be formed without using a vacuum process.
Therefore, since a chamber such as a vacuum chamber is not required, the size of the substrate can be increased, the process time for film formation can be shortened, and the cost can be reduced.

According to the second manufacturing method of the present invention, since the coating is performed by printing in the first manufacturing method, it can be formed without using a vacuum process.
Therefore, since a chamber such as a vacuum chamber is not required, the size of the substrate can be increased, the process time for film formation can be shortened, and the cost can be reduced.

According to the third manufacturing method of the present invention, in the first manufacturing method, since the coating is performed by ink jet, it can be formed without using a vacuum process. Therefore, since a chamber such as a vacuum chamber is not required, the size of the substrate can be increased, the process time for film formation can be shortened, and the cost can be reduced.

According to the fourth manufacturing method of the present invention, the first,
In the manufacturing method of 2 or 3, since a part or all of the silicon particle layer is converted into polysilicon by the laser irradiation, the polysilicon layer can be operated as a channel of the TFT.

According to the fifth manufacturing method of the present invention, the first,
In the manufacturing method of 2 or 3, since the conduction of the silicon particle layer is secured by the laser irradiation, it can be operated as a channel of the TFT.

According to the sixth manufacturing method of the present invention, the first,
In the manufacturing method of 2, 3, 4 or 5, since the silicon particles are single crystal silicon particles, the silicon particles are moved by melting the surface of the silicon particles with a smaller laser power than in the case of melting the entire silicon particles. A highly accurate silicon film can be formed.

According to the seventh manufacturing method of the present invention, the first,
In the manufacturing method of 2, 3, 4 or 5, since the silicon particles are polysilicon particles, the mobility can be improved by melting the surface of the silicon particles with a smaller laser power than in the case of melting the entire silicon particles. It is possible to form a high-quality silicon film.

According to the eighth manufacturing method of the present invention, the first,
In the manufacturing method of 2, 3, 4, 5, 6 or 7, since the insulating layer is formed by applying silicon oxide particles whose surface is covered with silicon oxide, it can be formed without using a vacuum process. Therefore, since a chamber such as a vacuum chamber is not required, the size of the substrate can be increased, the process time for film formation can be shortened, and the cost can be reduced.

According to the ninth manufacturing method of the present invention, the first,
In the manufacturing method of 2, 3, 4, 5, 6, 7 or 8,
Since the electrode is formed on the substrate and the contact layer is formed by coating donor-doped silicon particles and laser irradiation, the contact layer can be formed without using a vacuum process. Therefore, since a chamber such as a vacuum chamber is not required, the size of the substrate can be increased, the process time for film formation can be shortened, and the cost can be reduced.

According to a tenth manufacturing method of the present invention, in the first, second, third, fourth, fifth, sixth, seventh or eighth manufacturing method, an electrode is formed on a substrate, a contact layer and an acceptor are formed. Since it was formed by coating doped silicon particles and laser irradiation, it can be formed without using a vacuum process. Therefore, since a chamber such as a vacuum chamber is not required, the size of the substrate can be increased, the process time for film formation can be shortened, and the cost can be reduced.

Since the first thin film transistor of the present invention is obtained by the first, second, third, fourth, fifth, sixth, seventh, eighth, ninth or tenth manufacturing method, a chamber such as a vacuum chamber is not required and the substrate is not required. It is possible to increase the size, and the film forming process time is short, so that the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a diagram for explaining the manufacturing method according to the first embodiment.

FIG. 2 is a drawing for explaining the manufacturing method according to the second embodiment.

FIG. 3 is a drawing for explaining the manufacturing method according to the third embodiment.

FIG. 4 is a drawing for explaining the manufacturing method according to the fourth embodiment.

FIG. 5 is a diagram for explaining another manufacturing method of the fourth embodiment.

FIG. 6 is a diagram for explaining another manufacturing method of the fourth embodiment.

FIG. 7 is a diagram for explaining channel formation of a conventional TFT.

[Explanation of symbols]

1 Glass Substrate, 2 Silicon Particle Layer, 3 Channel Layer with Silicon Particle Surface Melted and Joined at Interface, 4 Polysilicon Layer, 5, 10, 11, 13 Si Particle Layer Covered with Oxide Film, 6 Drain Electrode , 7 source electrode,
8, 9 Donor-doped contact layer in which silicon particles are electrically connected to each other by laser irradiation 12 Gate electrode, 1
4 oxide film, 15 amorphous silicon film, 16 polysilicon film, 17 laser.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Kunihiko Nishimura             2-3 2-3 Marunouchi, Chiyoda-ku, Tokyo             Inside Ryo Electric Co., Ltd. (72) Inventor Norihisa Hashimoto             2-3 2-3 Marunouchi, Chiyoda-ku, Tokyo             Inside Ryo Electric Co., Ltd. F-term (reference) 5F052 AA02 DA01 DB10 EA11 JA01                 5F110 AA16 AA28 CC05 CC07 DD12                       DD13 DD21 DD25 FF02 FF27                       GG02 GG13 GG25 GG42 HK09                       HK14 HK21 HK31 HK32 PP03

Claims (11)

[Claims] 1. A step of applying silicon particles onto a substrate,
And a method for manufacturing a thin film transistor, which comprises the step of irradiating the silicon particles with a laser. 2. The method of manufacturing a thin film transistor according to claim 1, wherein the coating is performed by printing. 3. The method of manufacturing a thin film transistor according to claim 1, wherein the coating is performed by inkjet. 4. The method for manufacturing a thin film transistor according to claim 1, wherein a part or all of the silicon particle layer is converted into polysilicon by the laser irradiation. 5. The method for manufacturing a thin film transistor according to claim 1, 2 or 3, wherein conduction of the silicon particle layer is ensured by the laser irradiation. 6. The method of manufacturing a thin film transistor according to claim 1, wherein the silicon particles are single crystal silicon particles. 7. The method of manufacturing a thin film transistor according to claim 1, wherein the silicon particles are polysilicon particles. 8. The method according to claim 1, further comprising the step of applying silicon oxide particles whose surface is covered with silicon oxide onto the substrate.
2. The method for manufacturing a thin film transistor according to 2, 3, 4, 5, 6 or 7. 9. The method according to any one of claims 1 to 3, including the steps of forming an electrode on a substrate, applying donor-doped silicon particles, and irradiating the silicon particles with a laser beam.
4. A method of manufacturing a thin film transistor according to 4, 5, 6, 7 or 8. 10. The method according to claim 1, comprising the steps of forming an electrode on a substrate, applying acceptor-doped silicon particles, and irradiating the silicon particles with a laser.
2. A method of manufacturing a thin film transistor according to 2, 3, 4, 5, 6, 7 or 8. 11. The method according to claim 1, 2, 3, 4, 5, 6, 7,
A thin film transistor obtained by the manufacturing method according to 8, 9, or 10.