JP2001297984A - Forming method of polycrystalline silicon film, thin film transistor and its manufacturing method, and liquid crystal display device and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate difference in film quality of a polysilicon film, in a crystallization process when a low temperature polysilicon TFT is formed. SOLUTION: In the crystallization process in processes for manufacturing TFTs using a polycrystalline silicon film as a semiconductor layer, film is formation is performed by setting the film thickness of an amorphous silicon film to be most suitable when the crystallization process is performed by using energy of a constant laser beam. As a result, change of film quality of the polycrystalline silicon film can be reduced for the irregularity of the film thickness.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a polycrystalline silicon film, a thin film transistor, a method for manufacturing the same, a liquid crystal display device, and a method for manufacturing the same.

[0002]

2. Description of the Related Art As a method of manufacturing a semiconductor film of a thin film transistor (TFT), a non-crystalline semiconductor film (amorphous semiconductor and microcrystalline semiconductor) formed on a substrate such as glass is irradiated with laser light and melted. A laser annealing method is used to obtain a crystalline semiconductor film (a polycrystalline semiconductor and a single crystal semiconductor) by crystallization. This is usually called a crystallization step. As a laser light source, an argon laser, a KrF, and a XeCl excimer laser are generally used.
TFTs manufactured by the above-described manufacturing method are usually referred to as "low-temperature poly-Si-TFTs" because Si is mainly used as a semiconductor, and glass is mainly used as a substrate, and the process is configured at a temperature equal to or lower than the melting point of glass. Call. At present, amorphous S
A TFT using i as a semiconductor layer is generally used, and a circuit portion for driving a pixel uses a method in which an IC chip is mounted around a screen. By using a high-temperature low-temperature poly-Si-TFT, a driver circuit can be manufactured using a TFT formed over a glass substrate. By using a high-temperature low-temperature poly-Si-TFT, it is possible to reduce a portion having no screen in an outer peripheral portion of a panel of a liquid crystal display device, which is usually called a “frame”.

[0003]

However, in the above-mentioned crystallization step, a difference occurs in the film quality of the polycrystalline silicon film.
Further, when a TFT and a liquid crystal display device are manufactured using a polycrystalline silicon film having poor film quality or uneven film quality, defects such as TFT operation failure and screen luminance unevenness occur due to the characteristic difference. Further, when forming a high-definition TFT array including a driving circuit, or when trying to make the pixels of the liquid crystal display device high definition or narrowing the frame of the liquid crystal display device, a TFT having higher characteristics is required. And a crystalline silicon film is required.

[0004]

The optimum range of the thickness of the amorphous silicon film in the crystallization step was selected. Further, in the crystallization step, an optimal range of the relationship between the thickness of the amorphous silicon film and the irradiation energy density of the laser beam was selected.

[0005] (Claim 1) At least a step of forming an amorphous silicon film on a substrate, and irradiating the amorphous silicon film or the polycrystalline silicon film with a laser beam to melt and crystallize the film. Having a crystallization step of forming a polycrystalline silicon film or a monocrystalline silicon film, and selecting a film thickness of the amorphous silicon film or the polycrystalline silicon film from 41 nm to 90 nm, When the polycrystalline silicon was formed by irradiating the laser beam with a constant irradiation intensity, the variation in the film quality of the polycrystalline silicon film due to the thickness distribution in the substrate and the variation in the film thickness of the film formation was reduced.

(Claim 2) At least a step of forming an amorphous silicon film on a substrate, and irradiating the amorphous silicon film or the polycrystalline silicon film with a laser beam to melt and crystallize the film. A crystallization step of forming a polycrystalline silicon film or a monocrystalline silicon film, and selecting a film thickness of the amorphous silicon film or the polycrystalline silicon film from 45 nm to 70 nm, When the polycrystalline silicon was formed by irradiating the laser beam with a constant irradiation intensity, the variation in the film quality of the polycrystalline silicon film due to the thickness distribution in the substrate and the variation in the film thickness of the film formation was further reduced.

(Claim 3) At least a step of forming an amorphous silicon film on a substrate, and irradiating the amorphous silicon film or the polycrystalline silicon film with laser light to melt and crystallize the film. Having a crystallization step of forming a polycrystalline silicon film or a monocrystalline silicon film, and selecting a film thickness of the amorphous silicon film or the polycrystalline silicon film from 52 nm to 68 nm, Irradiation of laser light with a constant irradiation intensity to form polycrystalline silicon with high characteristics such as mobility reduces fluctuations in the quality of the polycrystalline silicon film due to film thickness distribution in the substrate and variations in film thickness. did.

(Claim 4) At least a step of forming an amorphous silicon film on a substrate, and irradiating the amorphous silicon film or the polycrystalline silicon film with a laser beam to melt and crystallize the film. A crystallization step of forming a polycrystalline silicon film or a monocrystalline silicon film, wherein the amorphous silicon film is formed with a transmittance of 0.3% or more and 7.6% or less, When the polycrystalline silicon was formed by irradiating the laser beam with the irradiation intensity, the variation in the film quality of the polycrystalline silicon film due to the thickness distribution in the substrate and the variation in the film thickness of the film formation was reduced.

(Claim 5) At least a step of forming an amorphous silicon film on a substrate, and irradiating the amorphous silicon film or the polycrystalline silicon film with a laser beam to melt and crystallize the film. A crystallization step of forming a polycrystalline silicon film or a single crystal silicon film, wherein the amorphous silicon film is formed so that the transmittance of the amorphous silicon film is in the range of 1.2% to 6.0%. When the polycrystalline silicon was formed by irradiating the laser beam with the irradiation intensity, the variation in the film quality of the polycrystalline silicon film due to the thickness distribution in the substrate and the variation in the film thickness of the film formation was reduced.

(Claim 6) At least a step of forming an amorphous silicon film on a substrate, and irradiating the amorphous silicon film or the polycrystalline silicon film with a laser beam to melt and crystallize the film. A crystallization step of forming a polycrystalline silicon film or a single-crystal silicon film, wherein the amorphous silicon film is formed with a transmittance of 1.3% or more and 3.2% or less. When the polycrystalline silicon was formed by irradiating the laser beam with the irradiation intensity, the variation in the film quality of the polycrystalline silicon film due to the thickness distribution in the substrate and the variation in the film thickness of the film formation was reduced.

(Claim 7) At least a step of forming an amorphous silicon film on a substrate, and irradiating the amorphous silicon film or the polycrystalline silicon film with laser light to melt and crystallize the film. Forming a polycrystalline silicon film or a monocrystalline silicon film. The film thickness of the amorphous silicon film or the crystalline silicon film (Ta: unit nm) and the energy density of laser light (El : Unit mJ / cm ² ) (Formula 1) By forming polycrystalline silicon using a range satisfying 3.80Ta + 120 ≦ El ≦ 4.68Ta + 156, the film quality of the polycrystalline silicon film is excellent. Stable in condition.

(Claim 8) At least a step of forming an amorphous silicon film on a substrate, and irradiating the amorphous silicon film or the polycrystalline silicon film with a laser beam to melt and crystallize the film. Forming a polycrystalline silicon film or a monocrystalline silicon film. The film thickness of the amorphous silicon film or the crystalline silicon film (Ta: unit nm) and the energy density of laser light (El : Unit mJ / cm ² ) (Formula 2) By forming polycrystalline silicon using a film thickness and a laser beam energy density in a range satisfying 3.78Ta + 138 ≦ El ≦ 4.54Ta + 153, The film quality of the polycrystalline silicon film was stabilized in a better condition.

(9) At least a step of forming an amorphous silicon film on a substrate, and irradiating the amorphous silicon film or the polycrystalline silicon film with a laser beam to melt and crystallize the film. Having a step of forming a polycrystalline silicon film or a single crystal silicon film, the transmittance of the amorphous silicon film after film formation (T: unit%) and the energy density of laser light in the crystallization step (El: When the polycrystalline silicon is formed using a range in which the relationship with the unit (mJ / cm ² ) satisfies (Equation 3) -128log10T + 390 ≦ El ≦ −202log10T + 520, the film quality of the polycrystalline silicon film is good. And stable.

(Claim 10) At least a step of forming an amorphous silicon film on a substrate, and irradiating a laser beam to the amorphous silicon film or the polycrystalline silicon film to melt and crystallize the film. Having a step of forming a polycrystalline silicon film or a single crystal silicon film, the transmittance of the amorphous silicon film after film formation (T: unit%) and the energy density of laser light in the crystallization step (El: By forming polycrystalline silicon using the film thickness and the energy density of the laser beam, the relationship with (unit: mJ / cm ² ) satisfies (Equation 4) -152log10T + 425 ≦ El ≦ −202log10T + 520. The film quality of the crystalline silicon film was stabilized in a better state.

(Claim 11) By using the polycrystalline silicon film produced by the method according to any one of claims 1 to 3, characteristics such as mobility of the thin film transistor are stabilized.

(Claim 12) By using the polycrystalline silicon film produced by the method according to any one of claims 4 to 6, characteristics such as mobility of the thin film transistor are stabilized.

(Claim 13) By using the polycrystalline silicon film produced by the method according to claim 7 or 8,
Characteristics such as mobility of the thin film transistor are improved.

(Claim 14) By using the polycrystalline silicon film produced by the method according to claim 9 or 10, characteristics such as mobility of the thin film transistor are improved.

(Claim 15) At least a step of forming an amorphous silicon film on a substrate, and irradiating the amorphous silicon film or the polycrystalline silicon film with a laser beam to melt and crystallize the film. A crystallization step of forming a polycrystalline silicon film or a single crystal silicon film, and performing the crystallization step by the method according to any one of claims 1 to 3. It was possible to widen the margin regarding the film thickness at the time of forming the amorphous silicon film and the intensity at the time of laser light irradiation.

(Claim 16) At least a step of forming an amorphous silicon film on a substrate, and irradiating a laser beam to the amorphous silicon film or the polycrystalline silicon film to melt and crystallize the film. A crystallization step of forming a polycrystalline silicon film or a single crystal silicon film, and performing the crystallization step by the method of claim 4 to 6 to form a thin film transistor having high characteristics by forming an amorphous silicon film. It was possible to widen the margin regarding the film thickness at the time and the intensity at the time of laser light irradiation.

(17) At least a step of forming an amorphous silicon film on a substrate, and irradiating a laser beam to the amorphous silicon film or the polycrystalline silicon film to melt and crystallize the film. A crystallization step of forming a polycrystalline silicon film or a single crystal silicon film, and performing the crystallization step by the method according to claim 7 or 8. The margin for the film thickness at the time of film formation and the intensity at the time of laser light irradiation could be further widened.

(Claim 18) At least a step of forming an amorphous silicon film on a substrate, and irradiating the amorphous silicon film or the polycrystalline silicon film with a laser beam to melt and crystallize the film. And a crystallization step of forming a polycrystalline silicon film or a single crystal silicon film. The crystallization step is performed by the method according to claim 9, whereby a thin film transistor having high characteristics is formed by an amorphous silicon film. The margin for the film thickness at the time of film formation and the intensity at the time of laser light irradiation could be further widened.

(Embodiment 19) By using the thin film transistor manufactured by the method described in claim 15, the image unevenness of the liquid crystal display device is reduced.

(Claim 20) The use of the thin film transistor manufactured by the method of claim 16 reduces image unevenness of the liquid crystal display device.

(Claim 21) By using the thin film transistor manufactured by the method of claim 17, a liquid crystal display device with higher definition is obtained.

(Claim 22) By using the thin film transistor manufactured by the method of claim 18, a liquid crystal display device with higher definition is obtained.

(Claim 23) At least a step of forming the amorphous silicon film according to claim 1 on a substrate, and irradiating the amorphous silicon film or the polycrystalline silicon film with a laser beam. 4. A method of manufacturing a liquid crystal display device, comprising: a crystallization step of melting and crystallizing to form a polycrystalline silicon film or a single crystal silicon film, wherein the crystallization step is performed by the method according to claim 1. According to the method, image unevenness of the liquid crystal display device was reduced, and the production yield was improved.

(24) At least a step of forming the amorphous silicon film according to the above (1) on a substrate, and irradiating the amorphous silicon film or the polycrystalline silicon film with laser light. 7. A liquid crystal display device comprising a crystallization step of melting and crystallizing to form a polycrystalline silicon film or a single crystal silicon film, wherein the crystallization step is performed by the method according to claim 4. By using the manufacturing method, image unevenness of the liquid crystal display device was reduced, and the manufacturing yield was improved.

(Claim 25) At least a step of forming the amorphous silicon film according to claim 1 on a substrate, and irradiating the amorphous silicon film or the polycrystalline silicon film with laser light. 9. A liquid crystal display comprising a crystallization step of melting and crystallizing to form a polycrystalline silicon film or a single crystal silicon film, wherein the crystallization step is performed by the method according to claim 7 or 8. Device manufacturing method.

(Claim 26) At least a step of forming the amorphous silicon film according to claim 1 on a substrate, and irradiating the amorphous silicon film or the polycrystalline silicon film with a laser beam. A liquid crystal display comprising a crystallization step of melting and crystallizing to form a polycrystalline silicon film or a single crystal silicon film, wherein the crystallization step is performed by the method according to claim 9 or 10. Device manufacturing method.

When a TFT using a polycrystalline silicon film as a semiconductor layer is manufactured, the quality of the polycrystalline silicon film greatly affects the characteristics of the TFT. Polycrystalline silicon film is
It is formed by irradiating a laser beam to an amorphous silicon film formed on a substrate such as a glass and melting and solidifying the film. Almost the volume (film thickness) of the amorphous silicon film
By irradiating a laser beam with an optimum energy in proportion to the above, a polycrystalline silicon film having a large polycrystal grain size and good film quality is formed. However, when the film thickness is too small, the energy range of the laser beam from which good film quality can be obtained becomes very narrow. On the other hand, if the film thickness is too large, the heat applied to the film by the laser beam causes unevenness in the film thickness direction, so that good film quality cannot be obtained. In other words, when the crystallization process is performed with a constant laser beam energy, the amorphous silicon film is formed with an optimum film thickness so that the polycrystalline silicon film can be prevented from shifting in film thickness. Film quality change can be reduced.

In consideration of the above mechanism, an optimum range of the thickness of the amorphous silicon film was selected. Further, in the crystallization step, an optimal range of the relationship between the thickness of the amorphous silicon film and the irradiation energy density of the laser beam was selected.

[0033]

Embodiments of the present invention will be described below with reference to the drawings. Note that the amorphous silicon film 3 is used as a general term for an amorphous silicon film and a polycrystalline silicon film. The crystalline silicon film 9 is used as a general term for a polycrystalline silicon film and a single crystal silicon film. When defining the irradiation energy density of the laser beam 5,
Although it is necessary to calculate the irradiation area, when measuring the location distribution of the laser intensity, the area connecting the locations showing half the laser intensity at the location where the intensity is highest is defined as the illumination area. There are several possible locations for measuring the energy density (intensity) of the laser beam. However, it is necessary to take into account that the laser intensity changes, such as a chamber window. The laser energy density defined in the present invention is a value measured in a state and a position where the substrate is actually irradiated. Further, the transmittance of an amorphous silicon film refers to the transmittance of an amorphous silicon film, as described in the following embodiment, in which a base film 2 is first formed on a glass substrate 1, Light of a certain wavelength (mainly 400 nm) is irradiated, and the ratio A between the irradiated light amount and the transmitted light amount is determined. Next, the substrate on which the base film 2 is formed on the glass substrate 1 is similarly irradiated with light having a certain wavelength, and the ratio B between the irradiated light amount and the transmitted light amount is obtained. The percentage difference between the ratio A and the ratio B is the transmittance.

The conventional conditions for forming polycrystalline Si are as follows: the thickness of the amorphous silicon is 80 nm; the transmittance is 0.4%;
The ELA energy is 300 mJ / cm ² , the hole mobility of polycrystalline Si is 20 cm ² / VS, and the TFT mobility is 5 in n-ch.
0 cm2 / VS.

(Embodiment 1) A method for manufacturing a polycrystalline silicon film according to Embodiment 1 of the present invention will be described below.

First, for the purpose of preventing impurities from the substrate 1 on the substrate 1, for example, a film having a thickness of 3 is formed by TEOS-CVD.
A 00 nm SiO ₂ underlayer 2 is formed. Note that the thickness of the base film 2 is not limited to 300 nm, and various settings can be made. Although glass is used as the substrate 1 in the present embodiment, a plastic or a film may be used. A silicon nitride film can also be used as the base film, and there is no problem if the film thickness is 200 nm or more.

Next, an amorphous silicon film 3 is formed by a plasma CVD method (FIG. 1). In forming the amorphous silicon film 3, a low pressure CVD method may be used. The thickness of the amorphous silicon film 3 is 35 nm, 4
They were 2 nm, 50 nm, 60 nm and 75 nm. In a normal polycrystalline silicon film manufacturing method, the dehydrogenation step and the subsequent steps may be performed with a single film thickness on the entire surface of the substrate. However, in this embodiment, in order to clearly show the effect, amorphous silicon of each film thickness is used. The film 3 is subjected to an etching process using a mask, and the film thickness of the amorphous silicon film 3 is, for example, 50 n.
m, the film thickness is 50 nm, 47
nm, 44 nm, 41 nm, 38 nm, 35 nm, 32
nm. Substrates having other film thicknesses were treated similarly (FIG. 2).

In order to remove hydrogen in the formed amorphous silicon film 3, a heat treatment was performed at 450 ° C. for 1 hour as a dehydrogenation step.

Next, a laser annealing apparatus 4 shown in FIG.
The polycrystalline silicon film 9 is formed by melting and crystallizing the amorphous silicon film 3 by (ELA apparatus). The laser annealing apparatus 4 can move the substrate 1 vertically and horizontally. When the amorphous silicon film 3 is irradiated with the laser beam 5 at room temperature with an energy density of about 160 mJ / cm ² or more, melting and crystallization occur, and the polycrystalline silicon film 9 is formed. . In the present embodiment, Xe
One point was irradiated with laser light 35 times while moving the substrate 1 using a Cl pulse laser 4 (wavelength 308 nm). The number of irradiations of the laser beam 5 can be set variously. The energy density of the laser light 5 is represented by a value obtained by dividing the total amount of measured power by the irradiation area and the frequency, that is, the laser energy density.

The irradiation energy of the laser beam 5 was such that the laser beam 5 could form a good polycrystalline silicon film 9 at each film thickness. That is, 270 mJ / cm ² for a substrate with a film thickness of 35 nm and ² for a substrate with a film thickness of 42 nm.
325 mJ / cm ² , 6 for 95 mJ / cm ² , 50 nm substrate
For the substrate of 0nm for the substrate of 360mJ / cm ^2, 75nm was irradiated with 400 mJ / cm ^2.

After the crystallization step, the polycrystalline silicon film 9 has
Since a large number of dangling bonds are formed, the substrate is left in hydrogen plasma, for example, at 450 ° C. for 2 hours. The hydrogen content is about 2 × 10 20 atom cm ^-3 .

The following steps were performed to evaluate the formed polycrystalline silicon film. The polycrystalline silicon layer 9 is patterned by photo and dry etching. next,
For example, SiO2 is formed as a gate insulating film to a required thickness, for example, 100 nm by TEOS-CVD. The gate insulating film is patterned by photo and dry etching. Next, a necessary kind of dopant is implanted into the source and drain regions by an ion doping apparatus. A portion other than the source and drain portions is shielded by metal, and a tantalum film is formed by sputtering.

The Hall effect of the sample completed in the above steps was measured.

When the film thickness is 35 nm and the laser energy is 2
70mJ / cm^Two, 295 mJ / cm at 42 nm ^Two, 325 at 50 nm
mJ / cm^Two360 mJ / cm at 60 nm^Two400 mJ / c at 75 nm
m^TwoPolycrystalline silicon film formed under the conditions
FIG. 4 shows the hole mobility (μh) of the recon film. Also before
The hole mobility at the above film thickness and energy is 40 V
S / cm^TwoTable showing the range of energy showing characteristics exceeding
Is shown in FIG.

It can be seen that the film thickness near 60 nm has the widest allowable range for the film thickness when a high-performance polycrystalline silicon film is formed. Further, the thickness of the amorphous silicon is (1) 41 nm or more and 90 nm or less (2) 45 nm or more
By selecting 0 nm or less and (3) 52 nm or more and 68 nm or less, it is understood that the hole mobility of the polycrystalline silicon film is increased stepwise and the allowable range of the film thickness is widened.

(Embodiment 2) A method of manufacturing a polycrystalline silicon film according to Embodiment 2 of the present invention will be described below.

First, in the same manner as in the first embodiment,
An SiO ₂ underlayer ₂ having a thickness of 300 nm is formed thereon.
Next, an amorphous silicon film 3 is formed by a plasma CVD method (FIG. 1).

The transmittance of the amorphous silicon film 3 was measured by changing various film forming conditions such as a film forming temperature and a gas flow rate. In this embodiment mode, the film formation time is adjusted to 5
Various kinds of amorphous silicon films were formed. The spectral transmittance of an amorphous silicon film having a thickness of 50 nm is as shown in FIG. 5, and the transmittance differs depending on the measurement wavelength. The transmittance in the present embodiment was measured at a measurement wavelength of 400 nm. The transmittances of the five types of amorphous silicon films are 11%, 7.1%, and 4, respectively.
3%, 2.3% and 0.9%. Next, as a dehydrogenation step, heat treatment was performed at 450 ° C. for 1 hour.

Next, a laser annealing apparatus 4 shown in FIG.
The polycrystalline silicon film 9 is formed by melting and crystallizing the amorphous silicon film 3 by (ELA apparatus). The laser annealing apparatus 4 can move the substrate 1 vertically and horizontally. When the amorphous silicon film 3 is irradiated with the laser beam 5 at room temperature with an energy density of about 160 mJ / cm ² or more, melting and crystallization occur, and the polycrystalline silicon film 9 is formed. . In the present embodiment, Xe
One point was irradiated with laser light 35 times while moving the substrate 1 using a Cl pulse laser 4 (wavelength 308 nm). The number of irradiations of the laser beam 5 can be set variously. The energy density of the laser light 5 is represented by a value obtained by dividing the total amount of measured power by the irradiation area and the frequency, that is, the laser energy density. In order to clearly show the effect, the amorphous silicon film 3 of each thickness is subjected to an etching process by using a mask, and a portion of seven types of amorphous silicon having different thicknesses in one substrate is removed. Formed. The thicknesses of the etched amorphous silicon are 0 nm, 3 nm, 6 nm, 9 nm, and 12 n.
m, 15 nm, and 18 nm. The same treatment was applied to the substrates having the transmittance of all the amorphous silicon (FIG. 2).
Laser light 5 is applied to a substrate having a transmittance of 11% with an energy of 2
At 70 mJ / cm ² , 295 mJ / cm ² ,
325mJ / cm ² with respect to 4.3% of the substrate, 360 mJ / cm ² with respect to 2.3% of the substrate was irradiated with 400 mJ / cm ² with respect to relative 0.9% substrate.

After the crystallization step, the polycrystalline silicon film 9 has
Since a large number of dangling bonds are formed, the substrate is left in hydrogen plasma, for example, at 450 ° C. for 2 hours. The hydrogen content is about 2 × 10 20 atom cm ^-3 .

The following steps were performed to evaluate the formed polycrystalline silicon film. The polycrystalline silicon layer 9 is patterned by photo and dry etching. next,
For example, SiO ₂ is formed to a thickness required as a gate insulating film, for example, 100 nm by a TEOS-CVD method. The gate insulating film is patterned by photo and dry etching. Next, a necessary kind of dopant is implanted into the source and drain regions by an ion doping apparatus. A portion other than the source and drain portions is shielded by metal, and a tantalum film is formed by sputtering.

The Hall effect of the sample completed in the above process was measured.

[0053] Laser energy 270mJ / cm ² in the transmittance of the amorphous silicon is ^{11%, 295mJ / cm 2,} 4 to 7.1%.
325mJ / cm ² at 3% 360 mJ / cm ² at 2.3%, 0.9%
FIG. 6 shows the hole mobility (μh) of the polycrystalline silicon film when the polycrystalline silicon film was formed under the conditions of 400 mJ / cm ² and FIG. In addition, FIG. 6 shows a table showing a range of energy showing a characteristic in which the hole mobility at the transmittance and the energy exceeds 40 V · S / cm ² .

It can be seen that when the transmittance of amorphous silicon is around 2%, the allowable range of the film thickness is the widest when a high-performance polycrystalline silicon film is formed. Further, the transmittance of the amorphous silicon is (1) 0.3% or more and 7.6% or less (2) 1.2% or more and 6% or less (3) 1.3% or more and 3.2%
It can be seen that selecting less than% increases the hole mobility of the polycrystalline silicon film in a stepwise manner and widens the allowable range of the film thickness.

In this embodiment, the transmittance is determined based on the transmittance after the amorphous silicon film is formed. However, after the amorphous silicon film is formed, dehydrogenation is performed. The same effect can be obtained by defining the amorphous silicon film using the transmittance of the crystalline silicon film. 11% transmittance after film formation,
7.1%, 4.3%, 2.3%, and 0.9% indicate that the amorphous silicon transmittance before laser irradiation is 7.2%, respectively.
They correspond to 4.3%, 2.4%, 1.1% and 0.4%.
Further, the transmittance of amorphous silicon during film formation in the specified range (1) 0.3% or more and 7.6% or less (2) 1.2% or more and 6% or less
(3) The transmittance before laser irradiation is (1) 0.1% or more and 4.6% or less (2) 0.
5% or more and 3.3% or less (3) 0.6% or more and 1.7% or less. Even when the transmittance at the time of film formation is described in the following mode, the same effect can be obtained by expressing the transmittance before laser irradiation.

(Embodiment 3) A method of manufacturing a polycrystalline silicon film according to Embodiment 3 of the present invention will be described below.

First, in the same manner as in the first embodiment,
An SiO ₂ underlayer ₂ having a thickness of 300 nm is formed thereon.
Next, an amorphous silicon film 3 is formed by a plasma CVD method (FIG. 1).

The thickness of the amorphous silicon film 3 is 40
nm, 50 nm, 55 nm, 60 nm and 70 nm. In order to remove hydrogen in the formed amorphous silicon film 3, a heat treatment at 450 ° C. for 1 hour was performed as a dehydrogenation step.

Next, a laser annealing apparatus 4 shown in FIG.
The polycrystalline silicon film 9 is formed by melting and crystallizing the amorphous silicon film 3 by (ELA apparatus). The laser annealing apparatus 4 can move the substrate 1 vertically and horizontally. When the amorphous silicon film 3 is irradiated with the laser beam 5 at room temperature with an energy density of about 160 mJ / cm ² or more, melting and crystallization occur, and the polycrystalline silicon film 9 is formed. . In the present embodiment, Xe
One point was irradiated with laser light 35 times while moving the substrate 1 using a Cl pulse laser 4 (wavelength 308 nm). The number of irradiations of the laser beam 6 can be set variously. The energy density of the laser light 5 is represented by a value obtained by dividing the total amount of measured power by the irradiation area and the frequency, that is, the laser energy density. The irradiation energy density of the laser beam 5 is 20
The crystallization step was performed while changing from 0 mJ / cm ² to 500 mJ / cm ² .

After the crystallization step, the substrate is left in a hydrogen plasma, for example, at 450 ° C. for 2 hours. Hydrogen content concentration is 2 × 10 20
It is about atom cm ^-3 .

Hereinafter, the following steps are performed similarly to the conventional TFT.

The following steps were performed to evaluate the formed polycrystalline silicon film. The polycrystalline silicon layer 9 is patterned by photo and dry etching. next,
For example, SiO ₂ is formed to a thickness required as a gate insulating film, for example, 100 nm by a TEOS-CVD method. The gate insulating film is patterned by photo and dry etching. Next, a necessary kind of dopant is implanted into the source and drain regions by an ion doping apparatus. A portion other than the source and drain portions is shielded by metal, and a tantalum film is formed by sputtering.

The Hall effect of the sample completed in the above process was measured.

Hole mobility (μh) of the polycrystalline silicon film subjected to the crystallization process at each film thickness and laser energy density
Is shown in FIG. The thickness of the amorphous silicon film 9 or the thickness of the polycrystalline silicon film (Ta: unit n
m) and the energy density of the laser beam (El: in relation to the units mJ / cm ^2), hole mobility 25V · S / cm ² or more characteristics,

[0065]

(Equation 1)

It can be seen that it can be obtained within the range satisfying. In addition, the characteristics with a hole mobility of 40 V · S / cm ² or more

[0067]

(Equation 2)

It can be seen that it can be obtained in the range satisfying.

It can be seen that by forming the polycrystalline silicon film in the range of the formulas 1 and 2, the characteristics of the polycrystalline silicon are improved and the margin of the forming process is expanded.

(Embodiment 4) A method of manufacturing a polycrystalline silicon film according to Embodiment 4 of the present invention will be described below.

First, as in the first embodiment, the substrate 1
An SiO ₂ underlayer ₂ having a thickness of 300 nm is formed thereon.
Next, five types of amorphous silicon films 3 were formed by plasma CVD using the film formation time as a parameter (FIG. 1).

The transmittance of the amorphous silicon film 3 is 8
%, 4.3%, 3.1%, 2.1%, and 1.2%.
As a dehydrogenation step, heat treatment was performed at 450 ° C. for 1 hour.

Next, the amorphous silicon film 3 is melted and crystallized by the same laser annealing apparatus 4 (ELA apparatus) as in the first embodiment shown in FIG. 3 to form a polycrystalline silicon film 9. In the present embodiment, one place was irradiated with laser light 35 times while moving the substrate 1 using the XeCl pulse laser 4 (wavelength 308 nm). Irradiation energy density of the laser light 5 was carried out the crystallization process by changing from 200 mJ / cm ² to 600 mJ / cm ^2.

After the crystallization step, the substrate is left in a hydrogen plasma, for example, at 450 ° C. for 2 hours. Hydrogen content concentration is 2 × 10 20
It is about atom cm ^-3 .

Hereinafter, the following steps are performed similarly to the conventional TFT.

The following steps were performed to evaluate the formed polycrystalline silicon film. The polycrystalline silicon layer 9 is patterned by photo and dry etching. next,
For example, SiO ₂ is formed to a thickness required as a gate insulating film, for example, 100 nm by a TEOS-CVD method. The gate insulating film is patterned by photo and dry etching. Next, a necessary kind of dopant is implanted into the source and drain regions by an ion doping apparatus. A portion other than the source and drain portions is shielded by metal, and a tantalum film is formed by sputtering.

The Hall effect of the sample completed in the above steps was measured.

The hole mobility (μ) of the polycrystalline silicon film subjected to the crystallization process at each transmittance and laser energy density
The graph showing h) is shown in FIG.

In the relationship between the transmittance (T: unit%) of the formed amorphous silicon film and the energy density of the laser beam (El: unit mJ / cm ² ), the hole mobility is 25 V · S / cm ^2. The above characteristics are

[0080]

(Equation 3)

It can be seen that it can be obtained in the range satisfying. In addition, the characteristics with a hole mobility of 40 V · S / cm ² or more

[0082]

(Equation 4)

It can be seen that it can be obtained within the range satisfying.

It can be seen that by forming the polycrystalline silicon film in the range of Equations 3 and 4, the characteristics of the polycrystalline silicon are improved, and the margin of the forming process is expanded.

(Embodiment 5) A method of manufacturing a thin film transistor according to Embodiment 5 of the present invention will be described below.

As in the first embodiment, first, a 300 nm-thick SiO ₂ underlayer 2 is formed on a substrate 1.

Next, an amorphous silicon film 3 is formed (FIG. 1). The thickness of the amorphous silicon film 3 is 35 nm,
42 nm, 50 nm, 60 nm and 75 nm. The transmittance after the formation of the amorphous silicon film of each thickness is 11%,
It is 7.1%, 4.3%, 2.3%, and 0.9%, and is expressed by a film thickness below.
Has the same effect.

In a normal TFT manufacturing method, the dehydrogenation step and the subsequent steps may be performed with a single film thickness on the entire surface of the substrate. However, in this embodiment, in order to clearly show the effect, amorphous silicon of each film thickness is used. The film 3 is subjected to an etching process using a mask.
In the case of nm, the film thickness is 50 nm, 4
7 nm, 44 nm, 41 nm, 38 nm, 35 nm, 3
It was set to 2 nm. Substrates having other film thicknesses were treated similarly (FIG. 2).

As a dehydrogenation step, heat treatment was performed at 450 ° C. for 1 hour.

Next, the laser annealing apparatus 4 shown in FIG.
The amorphous silicon film 3 is melted and crystallized by (ELA apparatus) to form a polycrystalline silicon film 9. The laser annealing apparatus 4 can move the substrate 1 vertically and horizontally. The crystallization step was performed in the same manner as in the first embodiment. The irradiation energy of the laser beam 5 is 270 mJ / cm ² for a substrate having a film thickness of 35 nm and ² for a substrate having a film thickness of 42 nm.
325 mJ / cm ² , 6 for 95 mJ / cm ² , 50 nm substrate
For the substrate of 0nm for the substrate of 360mJ / cm ^2, 75nm was irradiated with 400 mJ / cm ^2.

After the crystallization step, the substrate is left in a hydrogen plasma, for example, at 450 ° C. for 2 hours. Hydrogen content concentration is 2 × 10 20
It is about atom cm ^-3 .

Hereinafter, the following steps are performed similarly to the conventional TFT.

First, the polycrystalline silicon layer is patterned by photo and dry etching. Next, for example, TEO
SiO ₂ is formed as a gate insulating film to have a required thickness, for example, 100 nm by the S-CVD method. Next, molybdenum
A gate electrode is formed by sputtering a tungsten alloy film and patterning it into a predetermined shape by etching. Thereafter, a necessary kind of dopant is implanted into the source and drain regions by using the gate electrode as a mask by an ion doping apparatus. Further, an interlayer insulating film made of silicon oxide is formed by a TEOS-CVD method, the gate insulating film is covered, and a contact is formed between the interlayer insulating film and the silicon oxide film to reach the source region or the drain region of the polycrystalline silicon film by etching. Open a hole. Next, a titanium film and an aluminum-zirconium alloy film are sputtered and patterned into a predetermined shape by etching to form a source electrode and a drain electrode. Through the above process, a TFT is completed.

When the film thickness is 35 nm and the laser energy is 2
70mJ / cm^Two, 295 mJ / cm at 42 nm ^Two, 325 at 50 nm
mJ / cm^Two360 mJ / cm at 60 nm^Two400 mJ / c at 75 nm
m^TwoTFT transfer when a polycrystalline silicon film is formed under the above conditions
The mobilities are shown in FIG. In addition, the above-mentioned film thickness and energy
TFT mobility at 110V S / cm^TwoShows characteristics exceeding
FIG. 9 shows a table showing energy ranges.

It can be seen that the film thickness near 60 nm has the widest allowable range for the film thickness when a high-performance TFT is manufactured. The thickness of the amorphous silicon is (1) 41n.
It can be seen that by selecting from m to 90 nm, (2) from 45 nm to 70 nm, and (3) from 52 nm to 68 nm, the TFT mobility is increased step by step and the allowable range of the film thickness is widened. Similarly, the transmittance of amorphous silicon during film formation is (1) 0.3% or more and 7.6.
% Or less (2) 1.2% or more and 6% or less (3) By selecting 1.3% or more and 3.2% or less, the TFT mobility is increased step by step, and the allowable range of the film thickness is widened. You can see that.

(Embodiment 6) A method of manufacturing a thin film transistor according to Embodiment 6 of the present invention will be described below.

First, in the same manner as in the first embodiment,
An SiO ₂ underlayer ₂ having a thickness of 300 nm is formed thereon.
Next, an amorphous silicon film 3 is formed by a plasma CVD method (FIG. 1).

The thickness of the amorphous silicon film 3 is 40
nm, 50 nm, 55 nm, 60 nm and 70 nm. The transmittance of the amorphous silicon film during film formation is 8%, 4.
They are 3%, 1.9%, 2.3%, and 1.2%, and are represented by film thicknesses below. For example, the same effect can be obtained by replacing the film thickness of 40 nm with the transmittance of 8%.

In order to remove hydrogen in the formed amorphous silicon film 3, a heat treatment was performed at 450 ° C. for 1 hour as a dehydrogenation step.

Next, the amorphous silicon film 3 is melted and crystallized by the laser annealing device 4 (ELA device) in the same manner as in the first embodiment shown in FIG.
To form The irradiation energy density of the laser beam 5 is 20
The crystallization step was performed while changing from 0 mJ / cm ² to 600 mJ / cm ² .

After the crystallization step, the substrate is left in a hydrogen plasma, for example, at 450 ° C. for 2 hours. Hydrogen content concentration is 2 × 10 ²⁰
It is about atom cm ^-3 .

In the same manner as in the third embodiment, the polycrystalline silicon layer 9 is patterned, a gate insulating film is formed, and a molybdenum-tungsten alloy film is formed by sputtering and patterned to form a gate electrode. After that, necessary types of dopants are implanted into the source and drain regions. Further, an interlayer insulating film is formed, and a contact hole is opened by etching. Next, a source electrode and a drain electrode are formed by sputtering and patterning the titanium film and the aluminum-zirconium alloy film. Through the above process, a TFT is completed.

FIG. 1 is a graph showing the mobility (μ) of the TFT subjected to the crystallization step at each film thickness and laser energy density.
0. In relation to the thickness of the amorphous silicon film 9 or the thickness of the crystalline silicon film (Ta: unit nm) and the energy density of the laser beam (El: unit mJ / cm ² ), the mobility is 70 V · S / It can be seen that the characteristic of cm ² or more can be obtained in a range satisfying (Equation 1) 3.80Ta + 120 ≦ El ≦ 4.68Ta + 156. In addition, mobility 1
It can be seen that a characteristic of 10 V · S / cm ² or more can be obtained in a range satisfying (Equation 2) 3.78Ta + 138 ≦ El ≦ 4.54Ta + 153.

Similarly, the transmittance (T: unit%) of the formed amorphous silicon film and the energy density of laser light (El: unit
With respect to mJ / cm ² ), it can be seen that a characteristic having a mobility of 70 V · S / cm ² or more can be obtained in a range satisfying (Equation 3): −128 log10T + 390 ≦ El ≦ −202 log10T + 520. In addition, mobility 1
It can be seen that a characteristic of 10 V · S / cm ² or more can be obtained in a range satisfying (Equation 4): −152 log10T + 425 ≦ El ≦ −202 log10T + 520.

It can be seen that by forming the polycrystalline silicon film within the ranges of (Equation 3) and (Equation 4), the characteristics of the TFT are improved and the margin of the formation process is expanded.

(Embodiment 7) A method of manufacturing a liquid crystal display device according to Embodiment 6 of the present invention will be described below.

As in the first embodiment, first, a 300 nm-thick SiO ₂ underlayer 2 and an amorphous silicon film 3 are formed on a substrate 1 (FIG. 1). The thickness of the amorphous silicon film 3 is 35 nm, 42 nm, 50 nm, 60 nm and 7 nm.
5 nm. The transmittance after film formation is 11%,
The values are 7.1%, 4.3%, 2.3%, and 0.9%, and are expressed as film thicknesses below.
Has the same effect.

Normally, in the case of manufacturing a TFT, the dehydrogenation step and the subsequent steps may be performed with a single film thickness on the entire surface of the substrate. However, in this embodiment, in order to clearly show the effect, amorphous silicon of each film thickness is used. The film 3 is subjected to an etching process using a mask.
In the case of nm, the film thickness is 50 nm, 4
7 nm, 44 nm, 41 nm, 38 nm, 35 nm, 3
It was set to 2 nm. Substrates having other film thicknesses were treated similarly (FIG. 2).

As a dehydrogenation step, heat treatment was performed at 450 ° C. for 1 hour.

Next, the crystallization step shown in FIG. 3 was performed in the same manner as in the first embodiment. The irradiation energy of the laser beam 5 is
270 mJ / cm ² , 4 for a substrate with a film thickness of 35 nm
For the substrate of 2nm 295mJ / cm ^2, 3 for a substrate of 325mJ / cm ^2, 60nm for 50nm substrate
Irradiation was performed at 400 mJ / cm ² on a substrate of 60 mJ / cm ² and 75 nm.

After the crystallization step, the substrate is left in a hydrogen plasma, for example, at 450 ° C. for 2 hours. Hydrogen content concentration is 2 × 10 ²⁰
It is about atom cm ^-3 .

Thereafter, similarly to the third embodiment, the polycrystalline silicon layer 9 is patterned, a gate insulating film is formed, and a molybdenum-tungsten alloy film is formed by sputtering and patterned to form a gate electrode. After that, necessary types of dopants are implanted into the source and drain regions. Further, an interlayer insulating film is formed, and a contact hole is opened by etching. Next, a source electrode and a drain electrode are formed by sputtering and patterning the titanium film and the aluminum-zirconium alloy film. Through the above process, a TFT array substrate is completed.

The following steps are performed on the TFT array substrate,
The liquid crystal display device is completed. On one main surface of an insulating substrate, for example, a glass substrate of Corning's product number 1737, ITO
A counter electrode formed of a transparent conductive film such as that described above is formed to form a counter substrate. In addition, a polyimide film is formed on the opposite surface side of the array substrate and the opposite substrate, a polarizing plate is attached on the opposite surface side, and between the array substrate and the opposite substrate,
Liquid crystal is sandwiched and sandwiched.

When the film thickness is 35 nm and the laser energy is 2
70mJ / cm^Two, 295 mJ / cm at 42 nm ^Two, 325 at 50 nm
mJ / cm^Two360 mJ / cm at 60 nm^Two400 mJ / c at 75 nm
m^TwoTFT transfer when a polycrystalline silicon film is formed under the above conditions
The mobilities are shown in FIG. In addition, the film thickness and energy
TFT mobility is 110V ・ S / cm^TwoCharacteristics beyond
FIG. 9 shows a table showing the range of energy.

By forming the film at a thickness of about 60 nm, the characteristics of the TFT array were stabilized.

By improving the characteristics and stabilizing the TFT array,
Defects in the driving circuit of the liquid crystal display device were reduced, and defects such as uneven screen luminance were reduced. For example, with the transmittance of 0.9% after forming a film having a thickness of 75 nm, which has been conventionally used, the failure rate of the drive circuit was 35%, while the film thickness was 60 n.
The defect rate was reduced to 8% at a transmittance of 2.3% after film formation of m, and the screen luminance unevenness defect rate was 12% at a transmittance of 0.9% after film formation of a thickness of 75 nm. In the case of a transmittance of 2.3% after forming a film having a thickness of 60 nm, the transmittance decreased to 3%.

(Embodiment 8) A method of manufacturing a liquid crystal display device according to Embodiment 6 of the present invention will be described below.

First, as in the first embodiment, the substrate 1
An SiO ₂ underlayer 2 and an amorphous silicon film 3 having a thickness of 300 nm are formed thereon (FIG. 1). The thickness of the amorphous silicon film 3 was 40 nm, 50 nm, 55 nm, 60 nm and 70 nm. The transmittance of the amorphous silicon film at the time of film formation is 8%, 4.3%, 1.9%, 2.3%, 1.2%.
In the following description, the same effect can be obtained by replacing the film thickness of 40 nm with the transmittance of 8%. As a dehydrogenation step, heat treatment was performed at 450 ° C. for 1 hour.

Next, a crystallization step was performed in the same manner as in the first embodiment (FIG. 3). Irradiation energy density of the laser light 5 was carried out the crystallization process by changing from 200 mJ / cm ² to 600 mJ / cm ^2.

After the crystallization step, the substrate is left in a hydrogen plasma, for example, at 450 ° C. for 2 hours. Hydrogen content concentration is 2 × 10 ²⁰
It is about atom cm ^-3 .

Thereafter, similarly to the third embodiment, the polycrystalline silicon layer 9 is patterned, a gate insulating film is formed, and a molybdenum / tungsten alloy film is formed by sputtering and patterned to form a gate electrode. After that, necessary types of dopants are implanted into the source and drain regions. Further, an interlayer insulating film is formed, and a contact hole is opened by etching. Next, a source electrode and a drain electrode are formed by sputtering and patterning the titanium film and the aluminum film. Through the above process, a TFT array substrate is completed.

The following steps are performed on the TFT array substrate,
The liquid crystal display device is completed. On one main surface of an insulating substrate, for example, a glass substrate of Corning's product number 1737, ITO
A counter electrode formed of a transparent conductive film such as that described above is formed to form a counter substrate. In addition, a polyimide film is formed on the opposite surface side of the array substrate and the opposite substrate, a polarizing plate is attached on the opposite surface side, and between the array substrate and the opposite substrate,
Liquid crystal is sandwiched and sandwiched.

FIG. 1 is a graph showing the mobility (μ) of a TFT subjected to a crystallization step at each film thickness and laser energy density.
0. In relation to the thickness of the amorphous silicon film 9 or the thickness of the crystalline silicon film (Ta: unit nm) and the energy density of the laser beam (El: unit mJ / cm ² ), the mobility is 70 V · S / It can be seen that the characteristic of cm ² or more can be obtained in a range satisfying (Equation 1) 3.80Ta + 120 ≦ El ≦ 4.68Ta + 156. In addition, mobility 1
It can be seen that a characteristic of 10 V · S / cm ² or more can be obtained in a range satisfying (Equation 2) 3.78Ta + 138 ≦ El ≦ 4.54Ta + 153.

Similarly, the transmittance (T: unit%) of the formed amorphous silicon film and the energy density of laser light (El: unit
With respect to mJ / cm ² ), it can be seen that a characteristic having a mobility of 70 V · S / cm ² or more can be obtained in a range satisfying (Equation 3): −128 log10T + 390 ≦ El ≦ −202 log10T + 520. In addition, mobility 1
It can be seen that a characteristic of 10 V · S / cm ² or more can be obtained in a range satisfying (Equation 4): −152 log10T + 425 ≦ El ≦ −202 log10T + 520.

By using the step of crystallizing within the above range of the film thickness and the energy of the laser beam, the characteristics of the TFT array can be enhanced, the frame of the liquid crystal display device can be narrowed, and high definition pixels can be used. And the number of pixels in the screen can be increased.

[0126]

When a TFT using a polycrystalline silicon film as a semiconductor layer is manufactured, the film quality of the polycrystalline silicon film greatly affects the characteristics of the TFT. The polycrystalline silicon film is used when the amorphous silicon film formed on a substrate such as glass is irradiated with a laser beam, and is melted and solidified. By forming the film thickness or transmittance of the amorphous silicon film at an optimum value, a change in the film quality of the polycrystalline silicon film can be reduced with respect to the deviation of the film thickness. In consideration of the above mechanism, the optimum range of the thickness or transmittance of the amorphous silicon film was selected. By selecting (a) 41 nm or more and 90 nm or less, preferably (b) 45 nm or more and 70 nm or less, and more preferably (c) 52 nm or more and 68 nm or less as the thickness of the polycrystalline silicon film, the laser light is emitted at a constant irradiation intensity. Irradiation to form polycrystalline silicon, the variation in the film quality of the polycrystalline silicon film due to the thickness distribution in the substrate and the variation in the film thickness of the film formation is reduced,
1) The film quality of the polycrystalline silicon film was stabilized. 2) The characteristics of the thin film transistor were stabilized. 3) Defects in the driving circuit of the image display device were reduced, and image quality abnormalities such as uneven brightness of the image were reduced. The film thickness range is (a) 0.
It corresponds to 3% or more and 7.6% or less (b) 1.2% or more and 6% or less (c) 1.3% or more and 3.2% or less.

In the crystallization step, an optimum range of the relationship between the thickness of the amorphous silicon film and the irradiation energy density of the laser beam was selected. Thickness of amorphous silicon film (Ta: unit nm) and energy density of laser beam (El: unit mJ)
/ cm ² ) (Formula 1) TFT mobility by forming polycrystalline silicon using a film thickness and an energy density of laser light in a range satisfying 3.80Ta + 120 ≦ El ≦ 4.68Ta + 156. Can manufacture TFTs having characteristics of 70 V · S / cm ² or more. Further, the thickness of the amorphous silicon film (Ta: unit nm) and the energy density of the laser beam (El: unit mJ)
/ cm ² ) (Formula 2) Polycrystalline silicon is formed using a film thickness and a laser beam energy density in a range satisfying 3.78Ta + 138 ≦ El ≦ 4.54Ta + 153, or after forming the film. In the relationship between the transmittance of the amorphous silicon film (T: unit%) and the energy density of the laser beam (El: unit mJ / cm ² ), the mobility is 70%.
It can be seen that the characteristics of VS / cm ² or more can be obtained in a range satisfying (Equation 3): -128log10T + 390 ≦ El ≦ −202log10T + 520. In addition, mobility 1
The characteristics of 10 V · S / cm ² or more can be obtained in the range satisfying (Equation 4): −152 log10T + 425 ≦ El ≦ −202 log10T + 520. 1) The film quality of the polycrystalline silicon film is improved. 2) The characteristics of the thin film transistor have been improved, and it has become possible to stably manufacture a high-performance TFT having a TFT mobility of 110 V · S / cm ² or more. 3) The frame of the liquid crystal display device of the image display device can be narrowed, high-definition pixels can be used, and the number of pixels in the screen can be increased. For example,
Conventional setting: film thickness 75 nm, energy 350 mJ
/ cm ² , the width of the drive circuit portion that occupies most of the frame is 1
Although it was 2 mm, the film thickness was 60 nm and the energy was 400 mJ.
When the crystallization process is performed at a speed of / cm ² , a drive circuit
mm. In addition, in the setting of the conventional crystallization process, the limit is to form 320 × 200 pixels on a 4-inch screen, but the crystallization process with a film thickness of 60 nm and an energy of 400 mJ / cm ² has been considered. By using this, 640 × 400 pixels can be formed in the same 4-inch size.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a substrate before laser crystallization according to the present invention described in Embodiment 1.

FIG. 2 is a cross-sectional view illustrating a form of an amorphous silicon film before laser crystallization according to the present invention described in Embodiment 1;

FIG. 3 is a configuration diagram of a laser annealing apparatus according to the present invention described in Embodiment 1.

FIG. 4 is a graph showing hole mobility of a polycrystalline silicon film according to the present invention described in Embodiment 1;

FIG. 5 is a graph showing the spectral transmittance of the amorphous silicon film according to the present invention described in Embodiment 2;

FIG. 6 is a graph showing hole mobility of a polycrystalline silicon film according to the present invention described in Embodiment Mode 2;

FIG. 7 is a graph showing hole mobility of a polycrystalline silicon film according to the present invention described in Embodiment 3;

FIG. 8 is a graph showing hole mobility of a polycrystalline silicon film according to the present invention described in Embodiment 4;

FIG. 9 is a graph and a table showing TFT characteristics according to the present invention described in Embodiment 5;

FIG. 10 shows a TFT according to the present invention described in Embodiment 6;
Graph showing characteristics

[Explanation of symbols]

Reference Signs List 1 substrate (glass substrate) 2 underlayer (SiO ² ) 3 amorphous semiconductor film (amorphous silicon film) 4 laser device (XeCl excimer laser device) 5 laser beam 6 reflection mirror 7 optical attenuator (attenuator) 8 light Optical system for shaping 9 Crystalline semiconductor film (polycrystalline silicon film)

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yoshinabu Taketomi 1006 Kadoma, Kadoma, Osaka Prefecture F-term in Matsushita Electric Industrial Co., Ltd. (reference) 2H092 JB77 KA04 KA07 KA12 KB22 MA07 MA08 MA30 NA22 NA24 NA25 NA30 5C094 AA03 AA13 AA15 AA25 AA43 AA53 AA55 BA03 BA43 CA19 DA09 DA13 DB01 DB04 EA04 EA05 EA10 EB02 FA01 FB12 FB14 FB15 GB10 JA01 JA08 JA11 JA20 5F052 AA02 AA11 BB07 DA02 DB02 DB03 FA07 GC10 JA01 5F110 AA24 BB01 DD02GG02 DD02 DD02 DD02 GG45 GG47 HJ12 HL04 HL06 HL23 NN02 NN23 PP03 PP04 PP05 PP35 QQ11 QQ25

Claims (26)

[Claims] At least a step of forming an amorphous silicon film on a substrate, and irradiating the amorphous silicon film or the polycrystalline silicon film with a laser beam to melt and crystallize the film. Having a crystallization step of forming a crystalline silicon film or a single crystal silicon film, wherein in the crystallization step,
A method for manufacturing a polycrystalline silicon film, wherein the thickness of the amorphous silicon film or the thickness of the polycrystalline silicon film is 41 nm or more and 90 nm or less. 2. An amorphous silicon film or a polycrystalline silicon film is irradiated with a laser beam to melt and crystallize the amorphous silicon film or the polycrystalline silicon film. Having a crystallization step of forming a crystalline silicon film or a single crystal silicon film, wherein in the crystallization step,
A method for manufacturing a polycrystalline silicon film, wherein the thickness of the amorphous silicon film or the thickness of the polycrystalline silicon film is 45 nm or more and 70 nm or less. 3. At least a step of forming an amorphous silicon film on a substrate, and irradiating the amorphous silicon film or the polycrystalline silicon film with a laser beam to melt and crystallize the film. Having a crystallization step of forming a crystalline silicon film or a single crystal silicon film, wherein in the crystallization step,
A method for manufacturing a polycrystalline silicon film, wherein the thickness of the amorphous silicon film or the thickness of the polycrystalline silicon film is from 52 nm to 68 nm. 4. At least a step of forming an amorphous silicon film on a substrate, and irradiating the amorphous silicon film or the polycrystalline silicon film with a laser beam to melt and crystallize the film. A polycrystalline film having a crystallization step of forming a crystalline silicon film or a monocrystalline silicon film, wherein a transmittance of the amorphous silicon film after film formation is 0.3% or more and 7.6% or less. A method for manufacturing a silicon film. 5. At least a step of forming an amorphous silicon film on a substrate, and irradiating the amorphous silicon film or the polycrystalline silicon film with a laser beam to melt and crystallize the film. A polycrystalline film having a crystallization step of forming a crystalline silicon film or a monocrystalline silicon film, wherein a transmittance of the amorphous silicon film after film formation is 1.2% or more and 6.0% or less. A method for manufacturing a silicon film. 6. At least a step of forming an amorphous silicon film on a substrate, and irradiating the amorphous silicon film or the polycrystalline silicon film with a laser beam to melt and crystallize the film. A polycrystalline film having a crystallization step of forming a crystalline silicon film or a single-crystal silicon film, wherein a transmittance of the amorphous silicon film after the film formation is 1.3% or more and 3.2% or less. A method for manufacturing a silicon film. 7. At least a step of forming the amorphous silicon film according to claim 1 on a substrate, and irradiating the amorphous silicon film or the polycrystalline silicon film with laser light to melt the amorphous silicon film or the polycrystalline silicon film. Crystallizing to form a polycrystalline silicon film or a monocrystalline silicon film. In the crystallization step, the thickness of the amorphous silicon film or the thickness of the crystalline silicon film (Ta: unit nm) and the energy density of laser light (El: unit mJ / cm ² ) are within a range satisfying (Equation 1) 3.80Ta + 120 ≦ El ≦ 4.68Ta + 156. How to make a film. 8. At least a step of forming the amorphous silicon film according to claim 1 on a substrate, and irradiating the amorphous silicon film or the polycrystalline silicon film with laser light to melt the amorphous silicon film or the polycrystalline silicon film. Crystallizing to form a polycrystalline silicon film or a monocrystalline silicon film. In the crystallization step, the thickness of the amorphous silicon film or the thickness of the crystalline silicon film (Ta: unit nm) and the energy density of laser light (El: unit mJ / cm ² ) are within the range satisfying 3.78Ta + 138 ≦ El ≦ 4.54Ta + 153 (Equation 2). How to make a film. 9. At least a step of forming the amorphous silicon film according to claim 1 on a substrate, and irradiating the amorphous silicon film or the polycrystalline silicon film with laser light to melt the amorphous silicon film or the polycrystalline silicon film. Has a crystallization step of crystallizing and forming a polycrystalline silicon film or a single crystal silicon film, and the transmittance (T: unit%) of the amorphous silicon film after film formation and the laser light in the crystallization step. A method for producing a polycrystalline silicon film, wherein a relationship with an energy density (El: unit mJ / cm ² ) is within a range satisfying (Equation 3): -128log10T + 390 ≦ El ≦ −202log10T + 520. 10. A step of forming at least a non-crystalline silicon film according to claim 1 on a substrate, and irradiating the amorphous silicon film or the polycrystalline silicon film with laser light to melt the amorphous silicon film or the polycrystalline silicon film. Has a crystallization step of crystallizing and forming a polycrystalline silicon film or a single crystal silicon film, and the transmittance (T: unit%) of the amorphous silicon film after film formation and the laser light in the crystallization step. A method for producing a polycrystalline silicon film, wherein a relationship with an energy density (El: unit mJ / cm ² ) is within a range satisfying (Equation 4): -152log10T + 425 ≦ El ≦ −202log10T + 520. 11. A thin film transistor using a polycrystalline silicon film produced by the method according to claim 1. 12. A thin film transistor using a polycrystalline silicon film produced by the method according to claim 4. 13. A thin film transistor using a polycrystalline silicon film produced by the method according to claim 7. 14. A thin film transistor using a polycrystalline silicon film produced by the method according to claim 9. 15. At least a step of forming an amorphous silicon film on a substrate, and irradiating the amorphous silicon film or the polycrystalline silicon film with a laser beam to melt and crystallize the film. A method for manufacturing a thin film transistor, comprising a crystallization step of forming a crystalline silicon film or a single-crystal silicon film, wherein the crystallization step is performed by the method according to claim 1. 16. At least a step of forming an amorphous silicon film on a substrate, and irradiating the amorphous silicon film or the polycrystalline silicon film with a laser beam to melt and crystallize the film. 7. A method for manufacturing a thin film transistor, comprising: a crystallization step of forming a crystalline silicon film or a single-crystal silicon film, wherein the crystallization step is performed by the method according to claim 4. 17. At least a step of forming an amorphous silicon film on a substrate, and irradiating the amorphous silicon film or the polycrystalline silicon film with a laser beam to melt and crystallize the film. 9. A method for manufacturing a thin film transistor, comprising: a crystallization step of forming a crystalline silicon film or a single-crystal silicon film, wherein the crystallization step is performed by the method according to claim 7 or 8. 18. At least a step of forming an amorphous silicon film on a substrate, and irradiating a laser beam to the amorphous silicon film or the polycrystalline silicon film to melt and crystallize the film. A method for manufacturing a thin film transistor, comprising a crystallization step of forming a crystalline silicon film or a single-crystal silicon film, wherein the crystallization step is performed by the method according to claim 9 or 10. 19. A liquid crystal display device using a thin film transistor manufactured by the method according to claim 15. 20. A liquid crystal display device using a thin film transistor manufactured by the method according to claim 16. 21. A liquid crystal display device using a thin film transistor manufactured by the method according to claim 17. 22. A liquid crystal display device using a thin film transistor manufactured by the method according to claim 18. 23. At least a step of forming the amorphous silicon film according to claim 1 on a substrate, and irradiating the amorphous silicon film or the polycrystalline silicon film with laser light to melt the amorphous silicon film or the polycrystalline silicon film. 4. A liquid crystal display comprising a crystallization step of crystallizing to form a polycrystalline silicon film or a single crystal silicon film, wherein the crystallization step is performed by the method according to claim 1. Device manufacturing method. 24. At least a step of forming the amorphous silicon film according to claim 1 on a substrate, and irradiating the amorphous silicon film or the polycrystalline silicon film with laser light to melt the amorphous silicon film or the polycrystalline silicon film. 7. A liquid crystal display comprising a crystallization step of crystallizing to form a polycrystalline silicon film or a single crystal silicon film, wherein the crystallization step is performed by the method according to claim 4. Device manufacturing method. 25. At least a step of forming the amorphous silicon film according to claim 1 on a substrate, and irradiating the amorphous silicon film or the polycrystalline silicon film with laser light to melt the amorphous silicon film or the polycrystalline silicon film. 9. A method of manufacturing a liquid crystal display device, comprising: a crystallization step of crystallizing to form a polycrystalline silicon film or a single crystal silicon film, wherein the crystallization step is performed by the method according to claim 7 or 8. Method. 26. At least a step of forming the amorphous silicon film according to claim 1 on a substrate, and irradiating the amorphous silicon film or the polycrystalline silicon film with laser light to melt the amorphous silicon film or the polycrystalline silicon film. 11. A method of manufacturing a liquid crystal display device, comprising: a crystallization step of crystallizing to form a polycrystalline silicon film or a single crystal silicon film, wherein the crystallization step is performed by the method according to claim 9 or 10. Method.