JP2003115456A - Semiconductor device and method of forming it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve a problem in which the crystal grain size is as small as several nanometers to several ten nanometers because of a short melting time caused by a very short pulse width of a laser light emitted from an excimer laser and because of a low transmittance of the semiconductor film for the laser light. SOLUTION: This method is to form a semiconductor film having a large crystal-grain size by irradiating a crystalline semiconductor film formed by a thermal crystallization method utilizing metal elements with a laser light. Another constitution of this method is to form a semiconductor film having a low crystal-defect density and a large crystal-grain size by irradiating a crystalline semiconductor film formed by a thermal crystallization method utilizing metal elements with a laser light and by heat-treating again.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor device, and more particularly to a method for manufacturing a semiconductor device including a step of crystallizing an amorphous semiconductor film by heat treatment and laser annealing.

[0002]

2. Description of the Related Art In recent years, a technique for crystallizing an amorphous semiconductor film formed on an insulating substrate such as glass to form a semiconductor film having a crystalline structure (hereinafter referred to as a crystalline semiconductor film) has been widely studied. ing. As a crystallization method, a thermal annealing method using a furnace annealing furnace, a rapid thermal annealing method (RTA method), a laser annealing method, and the like are being studied. For crystallization, any one of these methods or a combination of a plurality of methods can be used.

A crystalline semiconductor film has extremely high mobility as compared with an amorphous semiconductor film. Therefore, an active matrix type in which a thin film transistor (TFT) is formed using this crystalline semiconductor film and TFTs for a pixel portion or for a pixel portion and a driving circuit are formed over one glass substrate, for example It is used for the liquid crystal display device of.

Usually, in order to crystallize an amorphous semiconductor film in a furnace annealing furnace, heat treatment at 600 ° C. or higher for 10 hours or longer is required. The substrate material applicable to this crystallization is quartz, but the quartz substrate is expensive, and it is very difficult to process it particularly in a large area. However, in order to improve the production efficiency, it is necessary to increase the area of the substrate, and in recent years, the use of a substrate having a side of more than 1 m has been considered.

On the other hand, the thermal crystallization method using a metal element disclosed in JP-A-7-183540 makes it possible to lower the crystallization temperature, which has been a problem in the past. The method is as follows:
It is possible to form a crystalline semiconductor film by adding a trace amount of an element such as palladium or lead and then performing a heat treatment at 550 ° C. for 4 hours.

On the other hand, since the laser annealing method can give high energy only to the semiconductor film without raising the temperature of the substrate so much, it can be used not only for a glass substrate having a low strain point but also for a plastic substrate or the like. This is a technology that is drawing attention because it can

As an example of the laser annealing method, a pulsed laser beam typified by an excimer laser is shaped by an optical system so that a square spot of several cm square or a linear shape with a length of 100 mm or more is formed on the irradiation surface. , Move the laser light
This is a method of performing annealing (or moving the irradiation position of the laser light relative to the irradiation target). In addition, the "line shape" here does not mean a "line" in a strict sense, but means a rectangle (or an oblong shape) having a large aspect ratio. For example, a laser beam having an aspect ratio of 2 or more (preferably 10 to 10000) but having a rectangular shape on the irradiation surface (rectangular beam)
There is no difference in being included in. Note that the linear shape is for ensuring energy density for performing sufficient annealing on the irradiation target, and sufficient annealing can be performed on the irradiation target even if it is rectangular or planar. It doesn't matter.

The crystalline semiconductor film thus produced is formed by aggregating a plurality of crystal grains, and the positions and sizes of the crystal grains are random. A TFT formed on a glass substrate is formed by separating the crystalline semiconductor into island-shaped patterning for element separation.
In that case, it was not possible to form by specifying the position and size of the crystal grain. Compared with the inside of crystal grains, the interface (crystal grain boundary) of crystal grains has innumerable recombination centers and trap centers due to an amorphous structure and crystal defects. It is known that when carriers are trapped in the trap centers, the potential of the crystal grain boundary rises and becomes a barrier against the carriers, so that the current transport characteristics of the carriers are deteriorated. The crystallinity of the semiconductor film in the channel formation region is
However, it was almost impossible to form the channel formation region with a single crystal semiconductor film by eliminating the influence of crystal grain boundaries.

It is known that the growth distance of crystal grains is proportional to the product of crystallization time and growth rate. here,
The crystallization time is defined as the time from the generation of crystal nuclei in the semiconductor film to the end of the crystallization of the semiconductor film. Further, when the time from the melting of the semiconductor film to the end of crystallization is defined as the melting time, if the melting time is extended and the cooling rate of the semiconductor film is made slow, the crystallization time becomes long, and Crystal grains of a grain size can be formed.

[0010]

In the laser annealing method, the crystallization by the excimer laser has a very short pulse width of several tens ns of laser light. Therefore, when a semiconductor film is irradiated with laser light using such a laser, the semiconductor film is melted and then cooled rapidly. As a result, the melting time becomes short, and the size of the crystal grain becomes very small, about several nm to several tens of nm.

Here, the reflectance, the transmittance and the absorptance with respect to the wavelength of the amorphous silicon film having a film thickness of 55 nm formed on the 1737 glass substrate in FIG. 1 are formed on the 1737 glass substrate in FIG. The reflectance, the transmittance, and the absorptance with respect to wavelength in a crystalline silicon film having a film thickness of 55 nm are shown. The crystalline silicon film is obtained by crystallizing an amorphous silicon film by a thermal annealing method using a metal element (here, nickel). Note that FIG. 3 shows the reflectance and the transmittance with respect to the wavelength of the 1737 glass substrate.

A typical excimer laser is a XeCl excimer laser, and the wavelength of oscillating laser light is 308 nm. As shown in FIGS. 1 and 2, when the wavelength is 308 nm, the absorption coefficient for the semiconductor film is high, so that the laser light does not penetrate into the film and only the vicinity of the surface is selectively heated. As a result, the melting time of the semiconductor film is shortened and the size of the crystal grain is reduced.

The present invention has been made in view of the above problems, and provides a technique capable of increasing the crystal grain size in a crystalline semiconductor film obtained by crystallizing an amorphous semiconductor film. The purpose is to do.

[0014]

In order to solve the above problems, a method of manufacturing a semiconductor device according to the present invention is a method of crystallizing an amorphous semiconductor film by heat treatment after adding a metal element to the amorphous semiconductor film. To form a first crystalline semiconductor film, and the first crystalline semiconductor film is pulsed with laser light having a wavelength of 350 nm or more and an energy density of 700 mJ / cm ^{2 to} 1800 mJ / cm ² a plurality of times. Irradiation is performed to form the second crystalline semiconductor film.

As another structure, after adding a metal element to the amorphous semiconductor film, the amorphous semiconductor film is crystallized by a first heat treatment to form a first crystalline semiconductor film.
The crystalline semiconductor film of is irradiated with pulsed laser light having a wavelength of 350 nm or more and an energy density of 700 mJ / cm ^{2 to} 1800 mJ / cm ² multiple times to form a second crystalline semiconductor film, A second heat treatment is performed on the second crystalline semiconductor film to form a third crystalline semiconductor film.

In the structure of the above invention, the wavelength is 350 nm.
Above, energy density is 700mJ / cm ^{2 to} 180
By irradiating the laser light with a pulse oscillation of 0 mJ / cm ² a plurality of times, the crystal grains of the crystalline semiconductor film can have a large grain size.

In the above structure, Fe, Co, Ni, Ru, Rh, Pd, Os, Ir and P are used as metal elements.
t, Cu, Ag, Au, Al, In, Sn, Pb, P,
One or more elements selected from As and Sb are applied. The heat treatment performed after adding such a metal element is preferably performed by a furnace annealing method or an RTA method.

Further, in the above structure, the laser beam is oscillated from a pulsed solid-state laser, a gas laser or a metal laser. As a solid-state laser, a pulsed YAG laser, YVO ₄
Laser, YLF laser, YAlO ₃ laser, glass laser, ruby laser, alexandride laser, Ti:
Sapphire laser or the like is applied.

Further, in the above structure, it is desirable that the laser light is converted into a harmonic by a non-linear optical element. For example, a YAG laser has a wavelength of 1 as a fundamental wave.
It is known to emit a 065 nm laser beam. The absorption coefficient of the laser beam for the silicon film is very low, and it is technically difficult to crystallize the amorphous silicon film which is one of the semiconductor films as it is. However, this laser light can be converted into a shorter wavelength by using a non-linear optical element, and the second harmonic wave (53
2 nm) and the third harmonic (355 nm) are desirable. Since these harmonics have a high absorption coefficient with respect to the amorphous silicon film,
It can be used for crystallization of an amorphous silicon film.

By irradiating the crystalline semiconductor film with laser light having a wavelength of 350 nm or more, the laser light penetrates into the crystalline semiconductor film, so that the semiconductor film is heated from the inside and the melting time becomes long. The particle size can be reduced.

In the above structure, it is desirable to use a silicon film as the amorphous semiconductor film. In addition to the amorphous silicon film, a compound semiconductor film having an amorphous structure such as an amorphous silicon germanium film may be applied. Then, a glass substrate, a quartz substrate, a silicon substrate, a plastic substrate, a metal substrate, a stainless substrate, a flexible substrate, or the like can be used as a substrate for forming the amorphous silicon film. Examples of the glass substrate include a substrate made of glass such as barium borosilicate glass or aluminoborosilicate glass. A flexible substrate is P
It is a film-shaped substrate made of ET, PES, PEN, acrylic, or the like, and if a semiconductor device is manufactured using a flexible substrate, weight reduction is expected. Aluminum film (AlON, Al
It is desirable to form a barrier layer such as N, AlO, etc.), a carbon film (DLC (diamond-like carbon), etc.), SiN, etc. in a single layer or in a multi-layer structure because the durability is improved.

The amorphous semiconductor film referred to in the present invention means
In a narrow sense, it includes not only a completely amorphous structure but also a state in which fine crystal grains are contained, a so-called microcrystalline semiconductor film, or a semiconductor film which locally includes a crystal structure. Typically, an amorphous silicon film is used, and in addition, an amorphous silicon germanium film, an amorphous silicon carbide film, or the like can be used.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to FIG.

First, as the substrate 10, a substrate made of glass such as barium borosilicate glass or aluminoborosilicate glass is used. As the substrate 10, a quartz substrate, a silicon substrate, a metal substrate, or a stainless steel substrate having an insulating film formed on the surface thereof may be used. Also,
A plastic substrate having heat resistance that can withstand the processing temperature of this embodiment may be used, or a flexible substrate may be used.

Then, a base film 11 made of an insulating film such as a silicon oxide film, a silicon nitride film or a silicon oxynitride film is formed on the substrate 10 by a known method. Although a two-layer structure is used as the base film 11 in this embodiment, a single layer film of the insulating film or a structure in which two or more layers are laminated may be used. Further, the base film 11 may not be formed.

Next, the semiconductor film 12 is formed on the base film 11. The semiconductor film 12 is formed by known means (sputtering method, LP
25 to 2 by the CVD method or the plasma CVD method)
A semiconductor film is formed with a thickness of 50 nm (preferably 30 to 200 nm). Examples of the semiconductor film include an amorphous semiconductor film, a microcrystalline semiconductor film, and a crystalline semiconductor film, and a compound semiconductor film having an amorphous structure such as an amorphous silicon germanium film may be applied.

Subsequently, the semiconductor film 12 is crystallized. For crystallization, a laser annealing method is performed after a thermal annealing method using a metal element. First, a metal element is introduced onto the semiconductor film 12 to form the metal-containing layer 13, and heat treatment by a thermal annealing method using a furnace annealing furnace or a RTA method is performed to form a semiconductor film having a crystalline region. In addition,
As the metal element, Fe, Co, Ni, Ru, Rh,
Pd, Os, Ir, Pt, Cu, Ag, Au, Al, I
One or more elements selected from n, Sn, Pb, P, As, and Sb can be used.

Then, a laser beam is applied to the obtained semiconductor film by 7
Greater than mJ / cm ^2, was irradiated with 1800 mJ / cm ² less than the energy density is carried out to improve the crystallization or crystalline. As the laser light, a wavelength having a high transmittance with respect to a semiconductor film having a wavelength of 350 nm or more (preferably 400 nm or more) is used. Further, although it is desirable to use a solid-state laser as the laser, a gas laser or a metal laser may of course be used. As the solid-state laser, continuous oscillation or pulse oscillation YAG laser, YVO ₄ laser, YLF laser, YAlO ₃ laser, glass laser,
There is a ruby laser, an alexandrite laser, a Ti: sapphire laser, and the like, and the gas laser includes a continuous oscillation or pulse oscillation KxF excimer laser, an Ar laser, a Kr laser, a CO ₂ laser, and the like, and the metal laser is helium cadmium. Laser, copper vapor laser,
A gold vapor laser is mentioned. Further, in each of the above configurations, it is desirable that the laser light be converted into a harmonic by a non-linear optical element.

Further, the laser annealing does not necessarily have to be performed on the entire surface of the semiconductor film, but can be performed only on a desired region.

The crystalline semiconductor film thus formed has crystal grains with a large grain size, and the grain size is 0.6 μm or more.

However, when the semiconductor film is irradiated with laser light having a high energy density, crystal defects may be formed. In that case, it is desirable to improve the crystal defects by heat treatment. The heat treatment is preferably performed at a temperature at which the semiconductor film is not melted. The heat treatment may be performed by a thermal annealing method using a furnace annealing furnace, a laser annealing method, an RTA method, or the like.

Since the crystalline semiconductor film thus formed has few crystal defects and has large-grain crystal grains, if a TFT is manufactured using the crystalline semiconductor film. , Its electrical characteristics are improved. Furthermore, the operating characteristics and reliability of a semiconductor device manufactured using such a TFT can be improved.

The present invention having the above construction will be described in more detail with reference to the following examples.

[0034]

EXAMPLES Example 1 In this example, an experiment conducted to confirm the effectiveness of the present invention will be described with reference to FIGS. 4 to 9.

First, as the substrate 10, 1 manufactured by Corning
A 737 glass substrate was used. Then, two layers of the base film 11 were laminated on the substrate 10. As the first layer 11a of the base film 11, a silicon oxynitride film (composition ratio Si = 32%, O = 27%) formed by using a plasma CVD method and using SiH ₄ , NH ₃ , and N ₂ O as reaction gases. , N = 24%, H =
17%) with a thickness of 50 nm, and the first layer 11b is a silicon oxynitride film (composition ratio Si = 32) formed by plasma CVD using SiH ₄ and N ₂ O as reaction gases.
%, O = 59%, N = 7%, H = 2%) with a thickness of 100 nm.

Next, the semiconductor film 12 is formed on the base film 11. As the semiconductor film 12, an amorphous silicon film is formed by plasma CV.
It is formed with a thickness of 54 nm by the D method.

Then, a first sample subjected to the first heat treatment and a second sample subjected to the second heat treatment were prepared. The first heat treatment is performed by adding nickel (10 ppm in terms of weight) as a metal element onto the semiconductor film by a solution coating method, and then in a furnace annealing furnace at 500 ° C. for 1 hour in a nitrogen atmosphere. It is a heat treatment performed at 550 ° C. for 4 hours. The second heat treatment is 500
It is a heat treatment performed in a nitrogen atmosphere at ℃ for 1 hour. In general, it is preferable to release hydrogen contained in the semiconductor film before irradiation with laser light,
Since it is possible to prevent the film surface from being roughened by performing a heat treatment at 00 ° C. for about 1 hour so that the amount of hydrogen contained is 5% or less of the total number of atoms contained in the semiconductor layer and then crystallizing the film,
The second heat treatment is performed.

Then, the first sample and the second sample are paired.
Output 20W, frequency 1kHz, pulse width 120nm
Using the YLF laser of
In other words, the energy density per pulse is changed to
Laser annealing was performed at a burlap rate of 98%.
Energy density is 464, 703, 956, 120
9, 1476, 1743, 1996, 2193, 241
8,2615mJ / cm ²And It should be noted that on the irradiation surface
The shape of the laser beam is 100 μm × 40 μm (both are 1 / e
²(Width) becomes linear, and the overlap rate is on the irradiation surface.
1 / e of beam profile²Width and substrate transfer speed
It is calculated from (2 mm / s).

The optical system used at this time is shown in FIG.
Shown in. The laser light emitted from the laser 21 travels with a divergence angle and is incident on a cylindrical lens 22 having a focal length of 50 mm. Since the cylindrical karun lens 22 is a lens having a curvature in only one direction, the laser light focuses only in one direction. Therefore, the shape of the laser light on the substrate 22 can be made linear, and the energy density can be increased as compared with the case where no cylindrical lens is used. Further, the laser light is obliquely incident on the substrate 23 and the stage 24 because the substrate 23
This is to prevent generation of so-called return light, in which the reflected light on the surface returns to the same optical path as when it is incident on the irradiation target. The return light is a factor that adversely affects the output and frequency of the laser, destroys the rod, and so on.

With respect to the sample thus obtained, the surface of the semiconductor film was observed with an optical microscope (dark field transmission mode, 100 ×). The result is shown in FIG. First
The sample of No. ² is still in an amorphous state at 700 mJ / cm ² , but sufficient crystallization is performed at 956 mJ / cm ² , and roughening of the film is observed at 1800 mJ / cm ² or more. For the second sample, 464 mJ
No description is given since it was impossible to take a picture at / cm ^{2 because} it was still in an amorphous state. At 956 mJ / cm ² , sufficient crystallization was performed, and 1800 mJ / cm
^{At 2} or more, roughening of the film is observed.

Therefore, the most crystallization is carried out.
6, 1209 and 1476 mJ / cm ² were subjected to SEM observation (30,000 times) to observe the size of crystal grains. First
FIG. 7 shows the observation result for the sample No. 1 and FIG. 8 shows the observation result for the second sample No. Further, FIG. 9 shows the average grain size calculated by measuring the grain size of the observed crystal grains. Figure 9
From this, it can be seen that the particle size increases as the energy density increases. Furthermore, it can be seen that the particle size of the first sample is significantly larger than that of the second sample.

From the above results, the effectiveness of the present invention was confirmed.

Further, as the energy density increases, crystal defects are observed in the first sample, but this can be improved by performing heat treatment by a known thermal annealing method at a temperature at which the semiconductor film is not melted.

In the present embodiment, a YLF laser is used as the laser and the second harmonic is converted, but the present invention is not limited to this. Also, the semiconductor film is not limited to the silicon film. Further, the optimum energy density of the laser light varies depending on the conditions such as the wavelength of the laser light, the pulse width, the absorptance and film thickness of the semiconductor film, the base film and the substrate.

Example 2 In this embodiment, the case of using a Ti: sapphire laser will be described with reference to FIG.

First, a glass substrate is used as the substrate 10, and a base film is formed on the glass substrate. In this embodiment,
As the base film 11, a silicon oxide film 50n is formed by the CVD method.
m, a silicon nitride oxide film of 50 nm is formed. Next, the semiconductor film 12 is formed on the base film 11. In this embodiment, an amorphous silicon film 54 nm is formed by the plasma CVD method.

Subsequently, the semiconductor film 12 is crystallized. For crystallization, a laser annealing method is performed after a thermal annealing method using a metal element. First, nickel is introduced onto the semiconductor film 12 to form the metal-containing layer 13, and heat treatment by the RTA method is performed to form a semiconductor film having a crystalline region.

Then, the obtained semiconductor film was 703 mJ /
greater than cm ^2, by irradiating a laser beam at 1743mJ / cm ² less than the energy density is carried out to improve the crystallinity. Further, as the laser light, a wavelength having a high transmittance with respect to a semiconductor film having a wavelength of 350 nm or more (preferably 400 nm or more) is used. Further, although it is desirable to use a solid-state laser as the laser, a gas laser or a metal laser may of course be used. As the solid-state laser, continuous oscillation or pulse oscillation YAG laser, YVO ₄ laser,
There are YLF lasers, YAlO ₃ lasers, glass lasers, ruby lasers, alexandrite lasers, Ti: sapphire lasers, and the like, and the gas lasers are continuous wave or pulsed KxF excimer lasers, Ar lasers,
There are Kr laser, CO ₂ laser and the like, and examples of the metal laser include helium cadmium laser, copper vapor laser and gold vapor laser. Further, in each of the above configurations,
It is desirable that the laser light be converted into higher harmonics by a non-linear optical element. In this embodiment, the pulse width is 10
Using the second harmonic of a 0 nm Ti: sapphire laser,
The semiconductor film is irradiated with an energy density of 1200 mJ / cm ² .

In this way, a crystalline semiconductor film having large crystal grains is formed.

However, when the semiconductor film is irradiated with laser light having a high energy density, crystal defects may be formed. In that case, it is desirable to improve the crystal defects by heat treatment. The heat treatment is preferably performed at a temperature at which the semiconductor film is not melted. The heat treatment may be performed by a thermal annealing method using a furnace annealing furnace, a laser annealing method, an RTA method, or the like. In this embodiment, heat treatment is performed at a temperature of 600 ° C. for 5 minutes by the RTA method.

Since the crystalline semiconductor film thus formed has few crystal defects and crystal grains having a large grain size, it is possible to fabricate a TFT using the crystalline semiconductor film. If so, its electrical characteristics are improved. Furthermore, the operating characteristics and reliability of a semiconductor device manufactured using such a TFT can be improved.

[Embodiment 3] In this embodiment, a method for manufacturing an active matrix substrate will be described with reference to FIGS. In this specification, a CMOS circuit and a driving circuit,
A substrate in which a pixel portion including a pixel TFT and a storage capacitor is formed over the same substrate is referred to as an active matrix substrate for convenience.

First, in this embodiment, a substrate 400 made of glass such as barium borosilicate glass or aluminoborosilicate glass is used. Note that as the substrate 400, a quartz substrate, a silicon substrate, a metal substrate, or a stainless substrate on which an insulating film is formed may be used.
Further, a plastic substrate having heat resistance that can withstand the processing temperature of this embodiment may be used, or a flexible substrate may be used. Since the present invention can easily form a linear beam having the same energy distribution, it is possible to efficiently anneal a large area substrate with a plurality of linear beams.

Then, a base film 401 made of an insulating film such as a silicon oxide film, a silicon nitride film or a silicon oxynitride film is formed on the substrate 400 by a known method. Although a two-layer structure is used as the base film 401 in this embodiment, a single layer film of the insulating film or a stacked structure of two or more layers may be used.

Next, a semiconductor film is formed on the base film.
The semiconductor film is formed by a known means (sputtering method, LPCVD method, plasma CVD method or the like) to a thickness of 25 to 200 nm (preferably 30 to 150 nm), and a thermal crystallization method using a metal element. After that, laser crystallization is performed to obtain a crystalline semiconductor film. These crystallization methods are performed by freely combining Example 1 or Example 2. In particular, the laser used in the laser crystallization method is preferably a pulsed solid-state laser. The solid-state laser is a pulsed YAG laser, YVO.
₄ laser, YLF laser, YAlO ₃ laser, glass laser, ruby laser, alexandride laser, Ti:
Examples include sapphire laser. Examples of the semiconductor film include an amorphous semiconductor film, a microcrystalline semiconductor film, and a crystalline semiconductor film, and a compound semiconductor film having an amorphous structure such as an amorphous silicon germanium film may be applied.

In this embodiment, a plasma CVD method is used,
A 50 nm amorphous silicon film is formed, and a thermal crystallization method and a laser crystallization method using a metal element that promotes crystallization are performed on the amorphous silicon film. Using nickel as the metal element,
After being introduced onto the amorphous silicon film by a solution coating method, 550
A first crystalline silicon film is obtained by performing heat treatment at 5 ° C. for 5 hours. Then, laser light emitted from a continuous wave YVO ₄ laser with an output of 10 W is converted into a second harmonic by a non-linear optical element, and then a linear beam is formed by an optical system to irradiate the second crystalline silicon. Get the curtain. The crystallinity is improved by irradiating the first crystalline silicon film with laser light to form the second crystalline silicon film. At this time, the wavelength of the laser light is 350 nm or more and the energy density is 703 m.
It is assumed that the energy density is higher than J / cm ^{2 and} lower than 1476 mJ / cm ² . At this time, the laser light
You may make it overlap about 0-98%.

Of course, using the first crystalline silicon film, T
Although an FT can be manufactured, the crystallinity of the second crystalline silicon film is improved and large-sized crystal grains are formed, so that the electrical characteristics of the TFT are improved. For example, the first
When a TFT is manufactured using the crystalline silicon film of No. 3, the mobility is about 300 cm ² / Vs, but when a TFT is manufactured using the second crystalline silicon film, the mobility is 500 to 600.
It is significantly improved to about cm ² / Vs.

Further, it is desirable to perform a heat treatment in order to improve the crystallinity. The heat treatment is a thermal annealing method using a furnace annealing furnace, a laser annealing method, an RTA method.
It may be done by law. At this time, it is desirable to perform processing at a temperature at which the semiconductor film does not melt. By performing this heat treatment, crystal defects are improved.

The crystalline semiconductor film thus obtained is subjected to a patterning process using a photolithography method to form semiconductor layers 402 to 406.

After forming the semiconductor layers 402 to 406, a slight amount of impurity element (boron or phosphorus) may be doped in order to control the threshold value of the TFT.

Next, a gate insulating film 407 which covers the semiconductor layers 402 to 406 is formed. The gate insulating film 407 is formed by a plasma CVD method or a sputtering method and has a thickness of 40 to
It is formed of an insulating film containing silicon with a thickness of 150 nm. In this embodiment, a silicon oxynitride film is formed with a thickness of 110 nm by a plasma CVD method. Of course, the gate insulating film is not limited to the silicon oxynitride film, and other insulating films may be used as a single layer or a laminated structure.

When a silicon oxide film is used, TEOS (Tetraethyl Ortho Silicat) is formed by the plasma CVD method.
e) and O ₂ are mixed, reaction pressure 40 Pa, substrate temperature 300
It can be formed by discharging at a high frequency (13.56 MHz) power density of 0.5 to 0.8 W / cm ² at a temperature of up to 400 ° C. The silicon oxide film produced in this way is
Good properties as a gate insulating film can be obtained by thermal annealing at 00 to 500 ° C.

Then, a film having a thickness of 20 is formed on the gate insulating film 407.
A first conductive film 408 having a thickness of 100 nm and a thickness of 100 to 4
A second conductive film 409 having a thickness of 00 nm is stacked. In this embodiment, a first conductive film 408 made of a TaN film having a thickness of 30 nm and a second conductive film 409 made of a W film having a thickness of 370 nm are stacked. The TaN film is formed by a sputtering method and is sputtered in an atmosphere containing nitrogen using a Ta target. The W film was formed by the sputtering method using a W target. Alternatively, it can be formed by a thermal CVD method using tungsten hexafluoride (WF ₆ ). In any case, it is necessary to reduce the resistance in order to use it as a gate electrode, and the resistivity of the W film is 20 μΩc.
It is desirable to be m or less.

In this embodiment, the first conductive film 408 is used.
Is TaN and the second conductive film 409 is W, but is not particularly limited, and Ta, W, Ti, Mo, Al, and C are all used.
It may be formed of an element selected from u, Cr, and Nd, or an alloy material or a compound material containing the above element as a main component. Alternatively, a semiconductor film typified by a polycrystalline silicon film doped with an impurity element such as phosphorus may be used. Also, A
A gPdCu alloy may be used.

Next, masks 410 to 415 made of resist are formed by using photolithography, and a first etching process for forming electrodes and wirings is performed. The first etching process is performed under the first and second etching conditions. (FIG. 10B) In this embodiment, as the first etching condition, ICP (Inductively Coupled Plasma:
(Inductively coupled plasma) etching method, CF ₄ , Cl ₂ and O ₂ are used as etching gases, the flow rate ratio of each gas is set to 25:25:10 (sccm), and the coil type electrode is applied at a pressure of 1 Pa. RF (13.56 MHz) power of 500 W is applied to the substrate to generate plasma for etching. RF (13.56 MHz) power of 150 W is also applied to the substrate side (sample stage) to apply a substantially negative self-bias voltage. The W film is etched under the first etching condition so that the end portion of the first conductive layer is tapered.

After that, the masks 410 to 110 made of resist are formed.
Without removing 415, the second etching condition was changed, CF ₄ and Cl ₂ were used as etching gases, and the respective gas flow rate ratios were set to 30:30 (sccm) to form a coil-type electrode at a pressure of 1 Pa. RF (13.56 MHz) power of 500 W is applied to generate plasma and etching is performed for about 30 seconds. 20W RF (13.56MH) on the substrate side (sample stage)
z) Apply power and apply a substantially negative self-bias voltage. Under the second etching condition in which CF ₄ and Cl ₂ are mixed, the W film and the TaN film are etched to the same extent.
Note that in order to perform etching without leaving a residue on the gate insulating film, the etching time may be increased at a rate of about 10 to 20%.

In the first etching process, the shape of the mask made of resist is made suitable,
The edges of the first conductive layer and the second conductive layer are tapered due to the effect of the bias voltage applied to the substrate side. The angle of this tapered portion is 15 to 45 °. Thus, the first shape conductive layers 417 to 422 (first conductive layers 417a to 422a and second conductive layers 417b to 42) including the first conductive layer and the second conductive layer are formed by the first etching treatment.
2b) is formed. 416 is a gate insulating film,
The area not covered with the conductive layers 417 to 422 in the shape of 20 is 20
A thinned region is formed by etching about 50 nm.

Next, a second etching process is performed without removing the resist mask. (FIG. 10C) In this case, the W film is selectively etched by using CF ₄ , Cl _2, and O _{2 as} etching gas. At this time, the second conductive layers 428b to 433b are formed by the second etching treatment. On the other hand, the first conductive layers 417a to 422a are
The second shape conductive layer 428 that is hardly etched
~ 433 is formed.

Then, the first doping process is performed without removing the resist mask, and the impurity element imparting n-type is added to the semiconductor layer at a low concentration. The doping treatment may be performed by an ion doping method or an ion implantation method. The condition of the ion doping method is that the dose amount is 1 × 10 ^{13 to} 5
The acceleration voltage is set to × 10 ¹⁴ / cm ² and the acceleration voltage is set to 40 to 80 keV. In this embodiment, the dose amount is 1.5 × 10 ¹³ / c.
m ² and the accelerating voltage is 60 keV. An element belonging to Group 15 is used as the impurity element imparting n-type, typically phosphorus (P) or arsenic (As), but phosphorus (P) is used here. In this case, the conductive layers 428 to 433
Serves as a mask for the impurity element imparting n-type, and impurity regions 423 to 427 are formed in a self-aligned manner. In the impurity regions 423 to 427, 1 × 10 ¹⁸ to 1 × 10 ²⁰ /
An impurity element imparting n-type is added within the concentration range of cm ³ .

After removing the resist mask, a new
In addition, masks 434a to 434c made of resist are formed.
The second acceleration voltage is higher than that of the first doping process.
Doping process. Ion doping conditions are dose
1 x 10¹³~ 1 x 10¹⁵/cm²And the acceleration voltage is 60
~ 120 keV. Doping process is the second guide
The electrode layers 428b to 432b serve as masks for impurity elements.
Used as a semiconductor layer below the tapered portion of the first conductive layer
Doping so that an impurity element is added to the. Continued
Lowering the acceleration voltage from the second doping process
A doping process is performed to obtain the state shown in FIG. I
The condition of the on-doping method is that the dose amount is 1 × 10 ¹⁵~ 1 x 10
¹⁷/cm²And the acceleration voltage is 50 to 100 keV.
U Second doping process and third doping process
As a result, the low-concentration impurity region 43 overlapping the first conductive layer is formed.
1 × 10 for 6,442,448¹⁸~ 5 x 10¹⁹/cm³of
An impurity element imparting n-type is added in the concentration range,
Impurity regions 435, 438, 441, 444, 447
For 1 x 10¹⁹~ 5 x 10^{twenty one}/cm³With n-type in the concentration range of
Impurity element to give is added.

Of course, by setting an appropriate acceleration voltage,
The second doping process and the third doping process are 1
It is possible to form the low-concentration impurity region and the high-concentration impurity region by performing the doping process once.

Next, after removing the resist masks, new resist masks 450a to 450 are formed.
c is formed and a fourth doping process is performed. By the fourth doping process, impurity regions 453 to 456, 4 in which an impurity element imparting a conductivity type opposite to the one conductivity type is added to a semiconductor layer which becomes an active layer of a p-channel TFT.
59 and 460 are formed. Second conductive layers 428a-43
Using 2a as a mask for the impurity element, the impurity element imparting p-type is added to form an impurity region in a self-aligned manner. In this embodiment, the impurity regions 453 to 456,
459 and 460 are formed by an ion doping method using diborane (B ₂ H ₆ ). (FIG. 11B) During this fourth doping process, the semiconductor layer forming the n-channel TFT is covered with masks 450a to 450c made of resist. Although phosphorus is added to the impurity regions 438 and 439 at different concentrations by the first to third doping processes, the concentration of the impurity element imparting p-type conductivity is set to 1 × 10 ^{19 to} 5 in any of the regions. × 10 ²¹
Doping so that the concentration of atoms / cm ³ causes no problem because it functions as a source region and a drain region of the p-channel TFT.

Through the above steps, the impurity regions are formed in the respective semiconductor layers.

Next, a mask 450a made of resist
To 450c are removed to form a first interlayer insulating film 461. As the first interlayer insulating film 461, plasma C is used.
The thickness is 100 to 200 using the VD method or the sputtering method.
It is formed of an insulating film containing silicon as nm. In this embodiment, a silicon oxynitride film having a thickness of 150 nm is formed by a plasma CVD method. Of course, the first interlayer insulating film 461 is not limited to the silicon oxynitride film, and another insulating film containing silicon may be used as a single layer or a laminated structure.

Next, as shown in FIG. 11C, heat treatment is performed to recover the crystallinity of the semiconductor layers and to activate the impurity elements added to the respective semiconductor layers. As the heat treatment, a thermal annealing method, a laser annealing method, a rapid thermal annealing method (RTA method) or the like can be applied.

For example, when the activation is carried out by the laser annealing method, a continuous oscillation or pulse oscillation solid-state laser, gas laser or metal laser is desirable. As the solid-state laser, continuous oscillation or pulse oscillation YA is used.
There are G laser, YVO ₄ laser, YLF laser, YAlO ₃ laser, glass laser, ruby laser, alexandrite laser, Ti: sapphire laser, and the like, and the gas laser includes a continuous oscillation or pulse oscillation excimer laser, Ar laser, Kr laser. Laser, CO ₂ laser, etc.
Examples of the metal laser include a continuous oscillation or pulse oscillation helium cadmium laser, a copper vapor laser, and a gold vapor laser. At this time, if a continuous wave laser is used, the energy density of the laser light is 0.01 to 10
0 MW / cm ² (preferably 0.01 to 10 MW /
cm ² ) is required, and the substrate is moved at a speed of 0.5 to 2000 cm / s relative to the laser light. If a pulsed laser is used, the frequency of 3
Laser energy density of 50 to 100
It is preferably 0 mJ / cm ² (typically 50 to 500 mJ / cm ² ). At this time, the laser beams may be overlapped by 50 to 98%.

Further, activation may be performed before forming the first interlayer insulating film. However, when the wiring material used is weak against heat, activation is performed after forming an interlayer insulating film (insulating film containing silicon as a main component, for example, a silicon nitride film) to protect the wiring and the like as in this embodiment. It is preferable to carry out a chemical treatment.

Then, heat treatment (1 to 300 at 550 ° C.
Hydrogenation can be performed by performing heat treatment for 12 hours. This step is a step of terminating the dangling bond of the semiconductor layer with hydrogen contained in the first interlayer insulating film 461. The semiconductor layer can be hydrogenated regardless of the presence of the first interlayer insulating film. Plasma hydrogenation (using hydrogen excited by plasma) as another means of hydrogenation
Or 300 to 45 in an atmosphere containing 3 to 100% hydrogen
You may perform heat processing for 1 to 12 hours at 0 degreeC.

Next, a second interlayer insulating film 462 made of an inorganic insulating film material or an organic insulating material is formed on the first interlayer insulating film 461. In this embodiment, the film thickness is 1.6 μm
The acrylic resin film of
cp, preferably 40 to 200 cp, and the one having irregularities on the surface is used.

In this embodiment, in order to prevent specular reflection, the second interlayer insulating film having unevenness on the surface is formed to form unevenness on the surface of the pixel electrode. Further, in order to make the surface of the pixel electrode uneven so as to achieve light scattering, a convex portion may be formed in a region below the pixel electrode. In that case, since the projection can be formed using the same photomask as that for forming the TFT, the projection can be formed without increasing the number of steps. Note that this convex portion may be appropriately provided on the substrate in the pixel portion region other than the wiring and the TFT portion. Thus, the unevenness is formed on the surface of the pixel electrode along the unevenness formed on the surface of the insulating film covering the convex portion.

A film having a flat surface may be used as the second interlayer insulating film 462. In that case, after forming the pixel electrode, a step such as a known sandblasting method or etching method is added to make the surface uneven so as to prevent specular reflection and scatter reflected light to increase the whiteness. Is preferred.

Then, in the drive circuit 506, wirings 464 to 468 electrically connected to the respective impurity regions.
To form. Note that these wirings have a thickness of 50 nm.
A laminated film of an i film and an alloy film (alloy film of Al and Ti) having a film thickness of 500 nm is formed by patterning. Of course, the structure is not limited to the two-layer structure, and may be a single-layer structure or a laminated structure of three or more layers. Also, as the wiring material,
It is not limited to Al and Ti. For example, Al or C on the TaN film
Wiring may be formed by forming u and then patterning a laminated film having a Ti film formed thereon. (Figure 12)

In the pixel portion 507, the pixel electrode 470, the gate wiring 469, and the connection electrode 468 are formed. By this connection electrode 468, the source wiring (a stack of 443a and 443b) is electrically connected to the pixel TFT. The gate wiring 469 is electrically connected to the gate electrode of the pixel TFT. Also, the pixel electrode 4
70 is electrically connected to the drain region 442 of the pixel TFT, and further electrically connected to the semiconductor layer 458 which functions as one electrode forming a storage capacitor. Further, as the pixel electrode 471, it is desirable to use a material having excellent reflectivity such as a film containing Al or Ag as a main component, or a laminated film thereof.

As described above, the n-channel TFT 50
1 and a p-channel TFT 502 CMOS circuit,
And driving circuit 506 having n-channel TFT 503
Then, the pixel portion 507 including the pixel TFT 504 and the storage capacitor 505 can be formed over the same substrate. Thus, the active matrix substrate is completed.

N-channel TFT 50 of drive circuit 506
Reference numeral 1 denotes a channel formation region 437, and a low-concentration impurity region 4 overlapping with the first conductive layer 428a forming part of the gate electrode.
36 (GOLD region), a high-concentration impurity region 452 functioning as a source region or a drain region, and an impurity region 451 in which an impurity element imparting n-type and an impurity element imparting p-type are introduced. A channel formation region 440, a high-concentration impurity region 454 functioning as a source region or a drain region, and an impurity element imparting n-type are provided in the p-channel TFT 502 which is connected to the n-channel TFT 501 with an electrode 466 to form a CMOS circuit. And an impurity region 453 in which an impurity element imparting p-type conductivity is introduced. In addition, the n-channel type TFT5
03 includes a channel formation region 443, a low-concentration impurity region 442 (GOLD region) overlapping with the first conductive layer 430a forming part of a gate electrode, a high-concentration impurity region 456 functioning as a source region or a drain region, and n. It has an impurity region 455 into which an impurity element imparting a type and an impurity element imparting a p-type are introduced.

In the pixel TFT 504 of the pixel portion, a channel forming region 446, a low concentration impurity region 445 (LDD region) formed outside the gate electrode, a high concentration impurity region 458 functioning as a source region or a drain region, and n.
It has an impurity region 457 into which an impurity element imparting a type and an impurity element imparting a p-type are introduced. Also,
An impurity element imparting n-type conductivity and an impurity element imparting p-type conductivity are added to the semiconductor layer functioning as one electrode of the storage capacitor 505. The storage capacitor 505 is formed of an electrode (a stack of 432a and 432b) and a semiconductor layer using the insulating film 416 as a dielectric.

In the pixel structure of the present embodiment, the end portion of the pixel electrode is arranged and formed so as to overlap the source wiring so that the gap between the pixel electrodes is shielded without using the black matrix.

A top view of the pixel portion of the active matrix substrate manufactured in this embodiment is shown in FIG. The same reference numerals are used for the parts corresponding to those in FIGS. A chain line AA ′ in FIG. 12 is a chain line AA ′ in FIG.
It corresponds to the cross-sectional view cut at. Further, the chain line BB ′ in FIG. 12 corresponds to the cross-sectional view taken along the chain line BB ′ in FIG. 13.

[Embodiment 4] In this embodiment, a process of manufacturing a reflective liquid crystal display device from the active matrix substrate manufactured in Embodiment 3 will be described below. FIG. 14 is used for the description.

First, according to the third embodiment, after obtaining the active matrix substrate in the state of FIG. 12, an alignment film 567 is formed on at least the pixel electrode 470 on the active matrix substrate of FIG. 12, and rubbing treatment is performed. In this embodiment, before forming the alignment film 567, the organic resin film such as the acrylic resin film is patterned to form the columnar spacers 572 for holding the substrate distance at desired positions. Further, spherical spacers may be dispersed over the entire surface of the substrate instead of the columnar spacers.

Next, the counter substrate 569 is prepared. Next, the coloring layers 570 and 571 and the planarization film 573 are formed over the counter substrate 569. The red colored layer 570 and the blue colored layer 571 are overlapped with each other to form a light shielding portion. In addition, the light-shielding portion may be formed by partially overlapping the red colored layer and the green colored layer.

In this example, the substrate shown in Example 3 is used. Therefore, FIG. 1 showing a top view of the pixel portion of the third embodiment.
3 at least the gate wiring 469 and the pixel electrode 470.
It is necessary to shield light from the gap between the gate wiring 469 and the connection electrode 468, and the gap between the connection electrode 468 and the pixel electrode 470. In this example, the colored layers were arranged so that the light-shielding portions formed by stacking the colored layers were overlapped with each other at the positions where they should be shielded, and the counter substrates were bonded together.

As described above, it is possible to reduce the number of steps by forming a light-shielding portion formed of a stack of colored layers so as to shield the gaps between pixels without forming a light-shielding layer such as a black mask.

Next, a counter electrode 576 made of a transparent conductive film was formed on the flattening film 573 at least in the pixel portion, an alignment film 574 was formed on the entire surface of the counter substrate, and a rubbing treatment was performed.

Then, a sealing material 568 is formed between the active matrix substrate on which the pixel portion and the driving circuit are formed and the counter substrate.
Stick together. A filler is mixed in the sealing material 568, and the two substrates are bonded to each other with a uniform interval by the filler and the columnar spacers. afterwards,
A liquid crystal material 575 is injected between both substrates and completely sealed with a sealant (not shown). A known liquid crystal material may be used as the liquid crystal material 575. In this way, the reflection type liquid crystal display device shown in FIG. 14 is completed. Then, if necessary, the active matrix substrate or the counter substrate is cut into a desired shape. Further, a polarizing plate (not shown) was attached only to the counter substrate. Then, using a known technique, F
I stuck a PC.

The liquid crystal display device manufactured as described above has a TFT manufactured using a semiconductor film having few crystal defects and large crystal grains, and the operation of the liquid crystal display device. The characteristics and reliability can be sufficient.
Then, such a liquid crystal display device can be used as a display portion of various electronic devices.

This embodiment can be freely combined with Embodiments 1 to 3.

[Embodiment 5] In this embodiment, an example in which a light emitting device is manufactured by using the method of manufacturing a TFT when manufacturing the active matrix substrate shown in Embodiment 3 will be described. In the present specification, a light emitting device is a generic term for a display panel in which a light emitting element formed on a substrate is enclosed between the substrate and a cover material, and a display module including a TFT on the display panel. is there. The light emitting element is
Luminescence generated by applying an electric field (Electro
It has a layer (light emitting layer) containing an organic compound capable of obtaining Luminescence, an anode layer, and a cathode layer. In addition, luminescence in an organic compound includes light emission when returning from a singlet excited state to a ground state (fluorescence) and light emission when returning from a triplet excited state to a ground state (phosphorescence). Alternatively, it includes both luminescence.

In the present specification, all layers formed between the anode and the cathode in the light emitting element are defined as organic light emitting layers. The organic light emitting layer specifically includes a light emitting layer, a hole injection layer, an electron injection layer, a hole transport layer, an electron transport layer, and the like. Basically, a light emitting device has a structure in which an anode layer, a light emitting layer, and a cathode layer are sequentially stacked. In addition to this structure, an anode layer, a hole injection layer, a light emitting layer, a cathode layer, and an anode layer are provided. It may have a structure in which a hole injecting layer, a light emitting layer, an electron transporting layer, a cathode layer and the like are laminated in this order.

FIG. 15 is a sectional view of the light emitting device of this embodiment. In FIG. 15, the switching TFT 603 provided on the substrate 700 is the n-channel TFT 50 of FIG.
3 is used. Therefore, the description of the structure may be referred to the description of the n-channel TFT 503.

Although the double gate structure in which two channel formation regions are formed is used in this embodiment, a single gate structure in which one channel formation region is formed or a triple gate structure in which three channel formation regions are formed may be used. good.

The driving circuit provided on the substrate 700 is shown in FIG.
It is formed using two CMOS circuits. Therefore, the description of the structure is given by the n-channel TFT 501 and the p-channel TFT.
The description of 502 may be referred to. Although a single gate structure is used in this embodiment, a double gate structure or a triple gate structure may be used.

Further, the wirings 701 and 703 function as a source wiring of the CMOS circuit, and 702 functions as a drain wiring.
The wiring 704 is connected to the source wiring 708 and the switching T.
The wiring 705 functions as a wiring that electrically connects the source region of the FT, and the wiring 705 is connected to the drain wiring 709 and the switching T.
It functions as a wiring that electrically connects the drain region of the FT.

The current control TFT 604 is p-type in FIG.
It is formed using the channel TFT 502. Therefore,
For the description of the structure, the description of the p-channel TFT 502 may be referred to. Although a single gate structure is used in this embodiment, a double gate structure or a triple gate structure may be used.

Further, the wiring 706 is a source wiring (corresponding to a current supply line) of the current control TFT, and 707 is an electrode electrically connected to the pixel electrode 711 by being overlapped on the pixel electrode 711 of the current control TFT. is there.

711 is a pixel electrode (anode of a light emitting element) made of a transparent conductive film. As the transparent conductive film,
A compound of indium oxide and tin oxide, a compound of indium oxide and zinc oxide, zinc oxide, tin oxide, or indium oxide can be used. Moreover, you may use what added gallium to the said transparent conductive film. The pixel electrode 711 has a flat interlayer insulating film 7 before the wiring is formed.
Form on 10. In this embodiment, it is very important to flatten the step due to the TFT by using the flattening film 710 made of resin. Since the light emitting layer that is formed later is very thin, the light emitting failure may occur due to the existence of the step. Therefore, it is desirable to flatten the light emitting layer before forming the pixel electrode so that the light emitting layer can be formed as flat as possible.

After forming the wirings 701 to 707, a bank 712 is formed as shown in FIG. Bank 712 is 10
It may be formed by patterning an insulating film containing 0 to 400 nm of silicon or an organic resin film.

Since the bank 712 is an insulating film,
Attention must be paid to the electrostatic breakdown of the device during film formation.
In this embodiment, carbon particles or metal particles are added to the insulating film that is the material of the bank 712 to lower the resistivity and suppress the generation of static electricity. At this time, the resistivity is 1 × 10 ⁶ to 1 × 1.
The addition amount of carbon particles or metal particles may be adjusted so as to be 0 ¹² Ωm (preferably 1 × 10 ⁸ to 1 × 10 ¹⁰ Ωm).

A light emitting layer 713 is formed on the pixel electrode 711. Although only one pixel is shown in FIG. 15, the light emitting layers corresponding to the colors R (red), G (green), and B (blue) are separately formed in this embodiment. Further, in this embodiment, the low molecular weight organic light emitting material is formed by the vapor deposition method.
Specifically, a 20-nm-thick copper phthalocyanine (CuPc) film is provided as a hole injection layer, and a 7-nm light emitting layer is formed thereon.
It has a laminated structure in which a 0 nm thick tris-8-quinolinolato aluminum complex (Alq ₃ ) film is provided. The emission color can be controlled by adding a fluorescent dye such as quinacridone, perylene or DCM1 to Alq ₃ .

However, the above example is an example of an organic light emitting material that can be used as a light emitting layer, and it is not necessary to limit to this. The light emitting layer (charge transporting layer or charge injecting layer) may be freely combined to form a light emitting layer (a layer for emitting light and for moving carriers therefor). For example, in this embodiment, an example in which a low molecular weight organic light emitting material is used as the light emitting layer is shown, but a medium molecular weight organic light emitting material or a high molecular weight organic light emitting material may be used. In the present specification, an organic light-emitting material having no sublimability and having a number of molecules of 20 or less or a chain of molecules having a length of 10 μm or less is referred to as a medium molecule organic light-emitting material. In addition, as an example of using a polymer organic light emitting material, the hole injection layer has a thickness of 20 nm.
Alternatively, a polythiophene (PEDOT) film may be provided by a spin coating method, and a para-phenylene vinylene (PPV) film having a thickness of about 100 nm may be provided on the polythiophene (PEDOT) film as a laminated structure. By using a PPV π-conjugated polymer, the emission wavelength can be selected from red to blue. Further, it is also possible to use an inorganic material such as silicon carbide for the charge transport layer and the charge injection layer. Known materials can be used as these organic light emitting materials and inorganic materials.

Next, a cathode 714 made of a conductive film is provided on the light emitting layer 713. In this embodiment, an alloy film of aluminum and lithium is used as the conductive film. Of course, a well-known MgAg film (an alloy film of magnesium and silver)
May be used. As the cathode material, a conductive film made of an element belonging to Group 1 or 2 of the periodic table or a conductive film to which those elements are added may be used.

When the cathode 714 is formed, the light emitting element 715 is completed. The light emitting element 71 referred to here
Reference numeral 5 denotes a diode formed by the pixel electrode (anode) 711, the light emitting layer 713 and the cathode 714.

It is effective to provide the passivation film 716 so as to completely cover the light emitting element 715. As the passivation film 716, an insulating film including a carbon film, a silicon nitride film, or a silicon nitride oxide film is used, and the insulating films are used as a single layer or a stacked layer in which they are combined.

At this time, it is preferable to use a film having good coverage as a passivation film, and a carbon film, especially D
It is effective to use an LC film. Since the DLC film can be formed in a temperature range from room temperature to 100 ° C. or lower, it can be easily formed over the light-emitting layer 713 having low heat resistance. In addition, the DLC film has a high blocking effect on oxygen and can suppress oxidation of the light emitting layer 713. Therefore, it is possible to prevent the problem that the light emitting layer 713 is oxidized during the subsequent sealing step.

Further, a sealing material 717 is provided on the passivation film 716, and a cover material 718 is attached. An ultraviolet curable resin may be used as the sealing material 717, and it is effective to provide a substance having a moisture absorption effect or a substance having an antioxidant effect inside. In this embodiment, the cover material 718 is a glass substrate, a quartz substrate, a plastic substrate (including a plastic film), or a flexible substrate having a carbon film (preferably a DLC film) formed on both sides. Besides carbon film, aluminum film (AlON, Al
N, AlO, etc.), SiN, etc. can be used.

Thus, the light emitting device having the structure shown in FIG. 15 is completed. Note that it is effective to continuously perform the steps from the formation of the bank 712 to the formation of the passivation film 716 using a multi-chamber system (or in-line system) film formation apparatus without exposing to the atmosphere. . Further, it is also possible to further develop and continuously process up to the step of attaching the cover material 718 without exposing to the atmosphere.

Thus, the n-channel type T is formed on the substrate 700.
FTs 601 and 602, a switching TFT (n-channel type TFT) 603 and a current control TFT (n-channel type TFT) 604 are formed.

Further, as described with reference to FIG.
By providing an impurity region overlapping the gate electrode with an insulating film interposed therebetween, n which is resistant to deterioration due to the hot carrier effect is used.
A channel TFT can be formed. for that reason,
It is possible to realize a highly reliable light emitting device.

Although only the configurations of the pixel portion and the driving circuit are shown in the present embodiment, a signal dividing circuit, a D / A converter, an operational amplifier, a γ correction circuit, etc. may also be used according to the manufacturing process of the present embodiment. Can be formed on the same insulator, and further, a memory and a microprocessor can be formed.

The light-emitting device manufactured as described above has a TFT manufactured using a semiconductor film having few crystal defects and having large-sized crystal grains. Credibility can be sufficient. And
Such a light emitting device can be used as a display portion of various electronic devices.

This embodiment can be freely combined with Embodiments 1 to 3.

[Embodiment 6] By applying the present invention, various semiconductor devices (active matrix type liquid crystal display device, active matrix type light emitting device, active matrix type E).
C display device) can be manufactured. That is, the present invention can be applied to various electronic devices in which those electro-optical devices are incorporated in the display unit.

Examples of such electronic devices include video cameras, digital cameras, projectors, head mounted displays (goggles type displays), car navigation systems, car stereos, personal computers, personal digital assistants (mobile computers, mobile phones, electronic books, etc.). ) And the like. Examples of these are shown in FIGS. 16, 17 and 18.

FIG. 16A shows a personal computer, which has a main body 3001, an image input section 3002, and a display section 30.
03, keyboard 3004 and the like. By applying the semiconductor device manufactured according to the present invention to the display portion 3003,
The personal computer of the present invention is completed.

FIG. 16B shows a video camera, which includes a main body 3101, a display portion 3102, a voice input portion 3103, operation switches 3104, a battery 3105, and an image receiving portion 310.
Including 6 etc. The video camera of the present invention is completed by applying the semiconductor device manufactured by the present invention to the display portion 3102.

FIG. 16C shows a mobile computer (mobile computer), which includes a main body 3201, a camera portion 3202, an image receiving portion 3203, operation switches 3204, a display portion 3205, and the like. The mobile computer of the present invention is completed by applying the semiconductor device manufactured by the present invention to the display portion 3205.

FIG. 16D shows a goggle type display, which includes a main body 3301, a display section 3302 and an arm section 330.
Including 3 etc. The goggle type display of the present invention is completed by applying the semiconductor device manufactured by the present invention to the display portion 3302.

FIG. 16E shows a player using a recording medium (hereinafter, referred to as a recording medium) in which a program is recorded, which is a main body 3401, a display portion 3402, a speaker portion 340.
3, a recording medium 3404, operation switches 3405 and the like. This player uses a DVD (D
optical Versatile Disc), CD
It is possible to play music, watch movies, play games, and use the internet. The recording medium of the present invention is completed by applying the semiconductor device manufactured according to the present invention to the display portion 3402.

FIG. 16F shows a digital camera, which includes a main body 3501, a display portion 3502, an eyepiece portion 3503, operation switches 3504, an image receiving portion (not shown) and the like. By applying the semiconductor device manufactured according to the present invention to the display portion 3502, the digital camera according to the present invention is completed.

FIG. 17A shows a front type projector including a projection device 3601, a screen 3602 and the like. The projection device 36 is a semiconductor device manufactured by the present invention.
01 is applied to the liquid crystal display device 3808 which constitutes a part of No. 01 and other drive circuits, the front type projector of the present invention is completed.

FIG. 17B shows a rear type projector, which includes a main body 3701, a projection device 3702 and a mirror 370.
3, screen 3704 and the like. By applying the semiconductor device manufactured by the present invention to the liquid crystal display device 3808 which forms a part of the projection device 3702 and other drive circuits, the rear projector of the present invention is completed.

Note that FIG. 17C is a diagram showing an example of the structure of the projection devices 3601 and 3702 in FIGS. 17A and 17B. Projection devices 3601, 37
02 is a light source optical system 3801, mirrors 3802, 380
4 to 3806, dichroic mirror 3803, prism 3807, liquid crystal display device 3808, retardation plate 380.
9, a projection optical system 3810. Projection optical system 38
Reference numeral 10 is composed of an optical system including a projection lens. Although the present embodiment shows an example of a three-plate type, it is not particularly limited and may be, for example, a single-plate type. In addition, the practitioner may appropriately provide an optical system such as an optical lens, a film having a polarization function, a film for adjusting a phase difference, and an IR film in the optical path indicated by an arrow in FIG. 17C. Good.

Further, FIG. 17D is a diagram showing an example of the structure of the light source optical system 3801 in FIG. 17C. In this embodiment, the light source optical system 3801 includes the reflector 3811, the light source 3812, the lens arrays 3813, and 3.
814, a polarization conversion element 3815, and a condenser lens 3816. Note that the light source optical system shown in FIG. 17D is an example and is not particularly limited. For example, the practitioner may appropriately provide an optical system such as an optical lens, a film having a polarization function, a film for adjusting a phase difference, and an IR film in the light source optical system.

However, the projector shown in FIG. 17 shows a case where a transmissive electro-optical device is used, and an application example of a reflective electro-optical device and a light emitting device is not shown.

FIG. 18A shows a mobile phone, which is a main body 39.
01, voice output unit 3902, voice input unit 3903, display unit 3904, operation switch 3905, antenna 3906
Including etc. The mobile phone of the present invention is completed by applying the semiconductor device manufactured according to the present invention to the display portion 3904.

FIG. 18B shows a portable book (electronic book) including a main body 4001, display portions 4002 and 4003, a storage medium 4004, operation switches 4005, an antenna 4006.
Including etc. By applying the semiconductor device manufactured by the present invention to the display portions 4002 and 4003, the portable book of the present invention is completed.

FIG. 18C shows a display, which includes a main body 4101, a support base 4102, a display portion 4103 and the like.
The display of the present invention is completed by applying the semiconductor device manufactured by the present invention to the display portion 4103. The display of the present invention is particularly advantageous when it has a large screen, and has a diagonal of 10 inches or more (particularly 30 inches or more).
Display is advantageous.

As described above, the applicable range of the present invention is so wide that it can be applied to electronic devices in various fields. Further, the electronic device of this embodiment can also be realized by using a configuration including a combination of the first to fourth or fifth embodiments.

[0139]

By adopting the structure of the present invention, the following basic significance can be obtained. (A) Fully compatible with the conventional TFT manufacturing process,
It has a simple configuration. (B) It becomes possible to form large-sized crystal grains with few crystal defects. (C) It is possible to reduce the running cost of the laser irradiation device. (D) In addition to satisfying the above advantages, in a semiconductor device represented by an active matrix type liquid crystal display device,
It is possible to improve the operating characteristics and reliability of the semiconductor device. Further, it is possible to reduce the manufacturing cost of the semiconductor device.

[Brief description of drawings]

FIG. 1 is a diagram showing reflectance, transmittance, and absorptance with respect to wavelength in an amorphous silicon film 55 nm.

FIG. 2 is a diagram showing reflectance, transmittance, and absorptance with respect to wavelength in a crystalline silicon film 55 nm.

FIG. 3 is a diagram showing reflectance and transmittance with respect to wavelength in a 1737 glass substrate.

FIG. 4 is a diagram showing the concept of the present invention.

FIG. 5 is a diagram showing an example of an optical system in laser annealing.

FIG. 6 is a diagram showing a result of observing the surface of a semiconductor film with an optical microscope when laser annealing is performed using a YLF laser.

FIG. 7 is a diagram showing a result of surface observation of a semiconductor film by SEM when laser annealing is performed using a YLF laser.

FIG. 8 is a diagram showing results of surface observation of a semiconductor film by SEM when laser annealing is performed using a YLF laser.

FIG. 9 is a diagram showing a comparison of particle size when laser annealing is performed using a YLF laser.

FIG. 10 is a cross-sectional view showing a manufacturing process of a pixel TFT and a driver circuit TFT.

11A to 11C are cross-sectional views illustrating a manufacturing process of a pixel TFT and a driver circuit TFT.

FIG. 12 is a cross-sectional view showing a manufacturing process of a pixel TFT and a driver circuit TFT.

FIG. 13 is a top view showing a configuration of a pixel TFT.

FIG. 14 is a cross-sectional view of an active matrix liquid crystal display device.

FIG. 15 is a cross-sectional structure diagram of a driver circuit and a pixel portion of a light emitting device.

FIG. 16 illustrates an example of a semiconductor device.

FIG. 17 illustrates an example of a semiconductor device.

FIG. 18 illustrates an example of a semiconductor device.

Continued front page    F term (reference) 2H092 KA05 MA29 MA30 NA13 NA21                 5C094 AA13 AA25 AA31 AA43 AA44                       AA53 BA03 BA27 BA43 CA19                       DA09 DA13 DB01 DB04 EA04                       EB02 FB12 FB14 FB15 GB10                       JA11 JA20                 5F052 AA02 AA11 AA17 AA24 BA01                       BA02 BA07 BB01 BB02 BB03                       BB04 BB05 DA02 DB03 EA15                       FA06 FA19 HA01 JA01                 5F110 AA01 AA30 BB02 BB04 BB05                       CC02 DD01 DD02 DD03 DD05                       DD13 DD14 DD15 DD17 EE01                       EE02 EE03 EE04 EE06 EE09                       EE14 EE23 EE28 EE44 EE45                       FF02 FF04 FF09 FF28 FF30                       GG01 GG02 GG13 GG16 GG25                       GG32 GG43 GG45 GG47 HJ01                       HJ04 HJ12 HJ13 HJ23 HL01                       HL03 HL04 HL06 HL11 HL12                       HM15 NN03 NN04 NN22 NN24                       NN27 NN34 NN35 NN36 NN73                       PP01 PP02 PP03 PP04 PP06                       PP07 PP10 PP13 PP29 PP34                       PP35 QQ04 QQ11 QQ19 QQ23                       QQ24 QQ25

Claims (9)

[Claims] 1. After adding a metal element to the amorphous semiconductor film,
The first crystalline semiconductor film is formed by crystallizing the amorphous semiconductor film by heat treatment, and forming a first crystalline semiconductor film on the first crystalline semiconductor film.
Wavelength is 350nm or more, energy density is 700mJ
/ cm ² to a laser beam pulse oscillation of 1800 mJ / cm ² was irradiated a plurality of times, a method for manufacturing a semiconductor device and forming a second crystalline semiconductor film. 2. After adding a metal element to the amorphous semiconductor film,
The amorphous semiconductor film is crystallized by a first heat treatment to form a first crystalline semiconductor film, and the first crystalline semiconductor film has a wavelength of 350 nm or more and an energy density of 7 nm.
The second crystalline semiconductor film is formed by irradiating a pulsed laser beam of 00 mJ / cm ^{2 to} 1800 mJ / cm ² multiple times,
A second heat treatment is performed on the second crystalline semiconductor film to obtain a third heat treatment.
And forming a crystalline semiconductor film thereof. 3. The method for manufacturing a semiconductor device according to claim 1, wherein the heat treatment is performed by a furnace annealing method or an RTA method. 4. The method according to claim 2, wherein the first heat treatment is
A method of manufacturing a semiconductor device, which is a furnace annealing method or an RTA method. 5. The heat treatment according to claim 2, wherein the first heat treatment is
A method for manufacturing a semiconductor device, which is performed by one or more selected from a furnace annealing method, a laser annealing method, and an RTA method. 6. The method for manufacturing a semiconductor device according to claim 1, wherein the laser light is emitted from a pulsed solid-state laser, a gas laser, or a metal laser. 7. The laser beam according to claim 1, 2, or 7, wherein the laser light is a pulse oscillation YAG laser, YVO ₄ laser, YLF laser, YAl.
A method of manufacturing a semiconductor device, which is oscillated from one selected from an O ₃ laser, a glass laser, a ruby laser, an alexandrite laser, and a Ti: sapphire laser. 8. The method for manufacturing a semiconductor device according to claim 1, 2, or 7, wherein the laser light is converted into a harmonic by a non-linear optical element. 9. The method for manufacturing a semiconductor device according to claim 1, wherein the amorphous semiconductor film is a film containing silicon.