JP2001345267A - Manufacturing method of semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve a TFT that can be operated speedily by manufacturing a crystalline semiconductor film where the position and size of a crystal particle are controlled, and, furthermore, using the crystalline semiconductor film for the channel formation region of the TFT. SOLUTION: A laser beam is emitted via a mask that allows laser light intensity to be modulated in desired space distribution and is made of a material that does not directly absorb the laser beam. The intensity distribution of the laser beam is reflected for forming temperature distribution inside a semiconductor device. By using the temperature distribution, the occurrence location and direction of lateral growth are controlled, and the large diameter of the crystal particle is manufactured at an arbitrary position on a substrate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a semiconductor film having a crystal structure formed on a substrate having an insulating surface, and a method for manufacturing a semiconductor device using the semiconductor film as an active layer. In particular, the present invention relates to a method for manufacturing a thin film transistor in which an active layer is formed using a crystalline semiconductor layer. Note that, in this specification, a semiconductor device refers to any device that can function by utilizing semiconductor characteristics, and includes an electro-optical device typified by an active matrix liquid crystal display device formed using a thin film transistor, and An electronic device having such an electro-optical device as a component is included in the category.

[0002]

2. Description of the Related Art A thin film transistor (hereinafter referred to as a thin film transistor) having an active layer formed of a crystalline semiconductor layer formed by forming an amorphous semiconductor layer on a light-transmitting insulating substrate such as glass and crystallizing the same by a laser annealing method or a thermal annealing method. Thin Film Transistor:
TFT) has been developed. As an insulating substrate, a glass substrate such as barium borosilicate glass or aluminoborosilicate glass is often used. Such a glass substrate is inferior in heat resistance to a quartz substrate, but is commercially available at a low price, and thus has an advantage that a large-area substrate can be easily manufactured.

[0003] The laser annealing method is known as a crystallization technique capable of giving high energy only to an amorphous semiconductor layer for crystallization by not raising the temperature of a glass substrate so much. In particular, an excimer laser capable of obtaining short-wavelength light and a large output is considered to be most suitable for this application. In laser annealing using an excimer laser, a laser beam is processed by an optical system so as to form a spot or a line on the surface to be irradiated, and the surface to be irradiated is scanned with the processed laser light (the laser light The irradiation position is moved relative to the irradiated surface). For example, in the excimer laser annealing method using linear laser light, it is possible to perform laser annealing on the entire irradiated surface by scanning only in a direction perpendicular to the longitudinal direction, and since liquid crystal using TFTs is excellent in productivity, It is becoming mainstream as a display device manufacturing technique. This technology has enabled a monolithic liquid crystal display device in which a pixel TFT forming a pixel portion on a single glass substrate and a TFT of a driving circuit provided around the pixel portion are formed.

However, a crystalline semiconductor layer produced by a laser annealing method is formed by assembling a plurality of crystal grains, and the positions and sizes of the crystal grains are random. TFT fabricated on a glass substrate is used for device isolation.
The crystalline semiconductor layer is formed separately in an island pattern. In that case, it was not possible to form the crystal grains by specifying the position and size of the crystal grains. The interface between crystal grains (grain boundaries) serves as a potential barrier to recombination centers, capture centers, and carriers due to the amorphous structure, crystal defects, and the like. For this reason, the crystal grain boundaries cause a reduction in the current transport characteristics of carriers. However, it has been almost impossible to form a channel forming region in which the properties of the crystal have a significant effect on the characteristics of the TFT with a single crystal grain excluding the influence of the crystal grain boundary. For this reason, a TFT using a crystalline silicon film as an active layer is a TFT manufactured on a single crystal silicon substrate.
Equivalent to transistor characteristics has not been obtained to date.

As a method of increasing the particle size, a method of leaving a solid phase only in a certain region and completely melting the other region during and immediately after laser irradiation can be considered. Hereinafter, this method will be described. In the solidification process after pulsed laser irradiation, it takes some time to generate solid phase nuclei in completely melted liquid silicon. Therefore,
If the solid phase silicon does not melt only at a certain position in the completely melted region but remains, the solid phase silicon is immediately used as a seed for crystal growth after laser irradiation.
As the crystal growth starts. During this time, the solid-liquid interface moves from the remaining solid phase silicon to the surrounding completely melted region, whereby crystal growth proceeds. It has been found that the distance that the solid-liquid interface moves in the horizontal direction (defined as a lateral direction in this specification) with respect to the film surface is several tens times the film thickness. (Defined herein as super lateral growth). It is believed that this super lateral growth is terminated by the occurrence of countless uniform nucleation (or heterogeneous nucleation) in the complete melting region. Attempts have been made to form large crystal grains by controlling the position by controlling the position of this method.

For example, "Grain location control by a
two-pass excimer laser crystallization process ",
L. Mariucci, R. Carluccio, A. Pecora, V. Foglietti, G.
Fortunato and D. Della Sala, Proc. AMLCD'99, pp283-2
86,1999 ", there is a method of laser crystallization via a metal mask. According to the method, a metal mask pattern is formed on a quartz substrate different from the sample substrate, the mask substrate is set on the sample substrate, and an excimer laser is irradiated through the mask. Large super laterally grown crystal grains are formed in the boundary region from the non-irradiation region directly below the mask pattern to the irradiation region.

[0007] Also, "" Grain Boundary Location contr
ol by Patterned Metal Film in Excimer Laser Crysta
llized Polysilicon ", L. Mariucci, R. Carluccio, A. Pe
cora, G. Fortunato, F. Massussi, V. Foglietti, D. Dell
a Sala and J. Stoemenos, Solid State Phenomena Vol
s. 67-68 (1999) pp. 175-180, a metal mask is formed on an upper layer of an amorphous semiconductor layer on a sample substrate, and is excimer laser crystallized. Also in this case, in the boundary region from the non-irradiation region directly below the mask pattern to the irradiation region,
Large crystal grains grown by super lateral growth are formed.

[0008]

The above-mentioned method of L. Mariucci et al. Is a method in which a large crystal grain size can be obtained at an arbitrary position on a substrate. However, metal contamination, metal film peeling, and metal etching after laser crystallization are performed. There is a problem of process difficulty. Hereinafter, these problems will be described.

When a metal is irradiated with a laser beam, the energy obtained by subtracting the reflected light energy from the irradiated laser beam energy is absorbed by the metal and converted into heat. When the metal mask is irradiated with laser light, the surface of the metal film is instantly heated to a high temperature. At this time, the temperature of the outermost surface rises to near the melting point, and ablation may occur. The ablated metal atoms are re-adhered to the active layer silicon and the laser device chamber and cause contamination. Even when ablation is not performed, film peeling occurs due to a difference in thermal stress caused by a difference in thermal expansion between the metal film and the metal mask substrate at a high temperature.

In the case of a method of forming a metal mask directly on a semiconductor layer to be an active layer, it is necessary to remove the metal mask after laser crystallization. At this time, it is difficult to selectively remove only the metal mask without damaging the active layer silicon.

The present invention is a technique for solving such a problem, in which a crystalline semiconductor film in which the positions and sizes of crystal grains are controlled is manufactured, and the crystalline semiconductor film is formed by a T
A TFT capable of high-speed operation is realized by using the TFT in a channel formation region of an FT. Further, it is another object of the present invention to provide a technique in which such a TFT can be applied to various semiconductor devices such as a transmission type liquid crystal display device and a display device using an electroluminescence material.

[0012]

The present invention uses the following method to solve the problem. A method in which laser light is passed through a mask consisting of a light-shielding area and a transmission area, and the laser light intensity is modulated so as to have a desired spatial distribution, and neither the light-shielding area nor the transmission area of the mask directly absorbs the laser light. Consist of material. When the semiconductor film is irradiated with the laser light whose intensity is spatially modulated in this manner, a temperature distribution is formed inside the semiconductor reflecting the laser light intensity distribution. By utilizing this, the location and direction of lateral growth are controlled to produce a large crystal grain size at an arbitrary position on the substrate.

In this method, since the mask does not absorb laser light, the mask itself does not generate heat. Accordingly, there is no influence of the metal film peeling and the metal contamination on the active layer silicon and the laser device chamber which occur in the case of the metal mask. Further, in the present method, the transmittance can be designed by the refractive index and the thickness of the thin film constituting the mask. Therefore, an arbitrary transmittance region can be formed at an arbitrary position on the mask. Hereinafter, this principle will be described.

The reflectance, transmittance and absorptivity when light is incident on a substance are determined by the optical constant, thickness and light wavelength of the substance. In particular, it is necessary to consider that the reflectivity, transmittance and absorptance of the thin film periodically fluctuate depending on the film thickness due to the interference effect. In the case of a multilayer film,
The reflectance, the transmittance, and the absorptance change according to the stacking order of each layer. In the case of the present invention, since the mask is made of a material having an attenuation constant at the wavelength of laser light of 0.1 or less, the absorptivity can be ignored.

FIG. 1 shows an example of transmittance when a silicon nitride film and a silicon oxide film are stacked on a quartz substrate. 96% or more depending on the thickness of the silicon nitride film and silicon oxide film
It can be seen that the transmittance can be greatly changed in the range of 30%.

FIG. 2 shows an example of the transmittance when a single layer of a silicon nitride film is laminated on a quartz substrate. In this case,
The transmittance can be changed in the range of 93% to 74%. The thicknesses of the silicon oxide and silicon nitride films forming the mask can be sufficiently controlled by the conventional CVD method.

When these thin films are patterned and formed into a desired shape and irradiated with a laser beam through a mask formed of a light shielding region and a transmission region, the intensity distribution of the laser beam is spatially modulated as shown in FIG. We can see that we can do it. By the above-described method, it was found that an arbitrary laser light intensity distribution can be realized at a desired position, so that a large crystal grain in which the location and direction of lateral growth can be controlled can be produced.

[0018]

[Embodiment 1] An embodiment of the present invention will be described with reference to FIG. In FIG. 4A, the substrate 40
For 1, a non-alkali glass substrate such as barium borosilicate glass or aluminoborosilicate glass is used. For example,
Corning's # 7059 glass or # 1737 glass base or the like can be suitably used. In addition, a plastic substrate having no optical anisotropy such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and polyethersulfone (PES) can be used. When a glass substrate is used, heat treatment may be performed in advance at a temperature lower by about 10 to 20 ° C. than the glass strain point. A base film 402 such as a silicon oxide film, a silicon nitride film, or a silicon oxynitride film is formed so as to be in close contact with one main surface of the substrate 401 where a TFT is to be formed and to prevent impurity diffusion from the substrate 401. For example, SiH ₄ in plasma CVD, NH _3, the N ₂ O silicon oxynitride film 402a made from 10 to 200 nm (preferably 50 to 100 nm), as well oxynitride made from SiH _4, N ₂ O The hydrogenated silicon film 402b is
The layer is formed to a thickness of 00 nm (preferably 100 to 150 nm).

The silicon oxynitride film is formed by using a conventional parallel plate type plasma CVD method. The silicon oxynitride film 402a is composed of 10 SCCM of SiH ₄ and 100 SC of NH ₃ .
CM and N ₂ O were introduced into the reaction chamber at 20 SCCM, the substrate temperature was 325 ° C., the reaction pressure was 40 Pa, and the discharge power density was 0.41 W / cm.
^{2. The} discharge frequency was 60 MHz. On the other hand, the silicon oxynitride silicon film 402b is made of ₅ SCCM of SiH ₄ and 120 SC of N ₂ O.
SCCM and H ₂ were introduced into the reaction chamber at 125 SCCM, and the substrate temperature was 400 ° C., the reaction pressure was 20 Pa, and the discharge power density was 0.41 W /
cm ² and a discharge frequency of 60 MHz. These films can be continuously formed only by changing the substrate temperature and switching the reaction gas. It is desirable to form such a base film so that the internal stress has a tensile stress with respect to the substrate in order to stabilize the threshold voltage (Vth). It is desirable that the internal stress does not change in the heat treatment at 400 to 600 ° C.

The silicon oxynitride film 402a manufactured in this manner has a density of 9.28 × 10 ²² / cm ³ , 7.13% of ammonium hydrogen fluoride (NH ₄ HF ₂ ) and ammonium fluoride (NH ₄ HF ₂ ). 20% of a mixed solution containing 15.4% of NH ₄ F) (trade name: LAL500, manufactured by Stella Chemifa).
The etching rate at a temperature of ° C. is as low as about 63 nm / min, and the film is dense and hard. The use of such a film as a base film is effective in preventing an alkali metal element from a glass substrate from diffusing into a semiconductor layer formed thereover.

Next, 25 to 80 nm (preferably 30 to 80 nm)
An amorphous semiconductor layer 403 having a thickness of 60 nm and having an amorphous structure is formed by a known method such as a plasma CVD method or a sputtering method. For example, an amorphous silicon film is formed to a thickness of 55 nm by a plasma CVD method. The semiconductor film having an amorphous structure includes an amorphous semiconductor layer and a microcrystalline semiconductor film, and a compound semiconductor film having an amorphous structure such as an amorphous silicon germanium film may be used. Further, both the base film 402 and the amorphous semiconductor layer 403 can be formed continuously. For example, as described above, the silicon oxynitride film 402a and the hydrogenated silicon oxynitride film 402b
Is continuously formed by a plasma CVD method, and then the reaction gas is changed to Si.
H _4, N ₂ O, be switched from H ₂ only SiH ₄ and H ₂ or SiH _4, once can be continuously formed without exposure to the atmosphere. As a result, the hydrogenated silicon oxynitride film 402b
To prevent contamination of the surface of the TFT
Characteristic variation and fluctuations in the threshold voltage can be reduced.

Next, a method of manufacturing a mask will be described. In this embodiment, apart from the sample substrate as described in claim 2,
A method of preparing a mask substrate and forming a mask thereon will be described. As the mask substrate 4010 shown in FIG. 4B, synthetic quartz, high silica glass, sapphire, or the like having high transmittance at the wavelength of laser light is used. For example, when synthetic quartz glass is used, the wavelength of XeCl excimer laser light is 3
The transmittance is 90% or more at 08 nm. A silicon nitride film and a silicon oxynitride film are formed over a substrate by a plasma CVD method so as to have a desired transmittance. For example, for a XeCl excimer laser beam having a wavelength of 308 nm, the transmittance is 3
When it is set to 0%, the refractive index is 1.4 as shown in FIG.
8 silicon nitride film 4040b and a silicon nitride film 4040a having a refractive index of 2.1 are formed on a synthetic quartz substrate by 35 nm silicon nitride film, 60 nm silicon oxynitride film, 35 nm silicon nitride film, and 60 nm silicon oxynitride film. , 35nm
May be formed in this order.

Thereafter, a resist mask is formed by using a photolithography technique, and the laminated thin film in a portion to be a transmission region is etched to form a mask pattern. For the insulating film, a dry etching method using a fluorine-based gas may be used, or a wet etching method using a fluorine-based aqueous solution may be used. When the latter method is selected, for example, ammonium hydrogen fluoride (NH ₄
HF ₂ ) at 7.13% and ammonium fluoride (NH ₄ F)
Is preferably etched with a mixed solution containing 15.4% (LAL500, manufactured by Stella Chemifa).

For crystallization, a laser annealing method is used.
In the crystallization step, first, it is desirable to release hydrogen contained in the amorphous semiconductor film, and it is preferable to perform a heat treatment at 400 to 500 ° C. for about one hour to reduce the amount of hydrogen contained to 5 atom% or less. .

When crystallization is performed by laser annealing, a pulse oscillation type or continuous emission type excimer laser, YAG laser, or argon laser is used as the light source. The laser annealing conditions are appropriately selected by the practitioner. For example, the pulse oscillation frequency of the excimer laser is 30 Hz, and the laser energy density is 2.
00 to 600 mJ / cm ² (typically 350 to 550 mJ / cm ² )
As a line width of 100 to 1000 μm, for example, a line width of 400
Irradiate a linear beam of μm. The irradiation may be performed a plurality of times while scanning the linear beam. The same processing can be performed even when the shape of the laser beam is planar.

As shown in FIG. 4C, the mask substrate 40
Numeral 10 is arranged on the surface of the sample substrate on which the amorphous semiconductor film is formed. At this time, the distance between the surface of the amorphous semiconductor film and the surface of the film forming the mask is desirably 1 to 50000 μm.

In the case of a laser beam having a wavelength of 308 nm, the transmittance of the light-shielded area is 30%, and the transmittance of the transparent area is 93%.
It is. Therefore, the intensity of the laser beam that has passed through the light-shielding region is smaller than the intensity of the laser beam that has passed through the transmission region of the mask substrate. For example, when irradiation is performed at a laser energy density of 550 mJ / cm ^2, the laser energy densities transmitted through the light shielding area and the transmission area of the mask substrate become 165 mJ / cm ² and 512 mJ / cm ² , respectively. In this case, although the amorphous silicon film 405 immediately below the transmission region is completely melted,
Immediately below the light-shielding region 406, only the vicinity of the surface of the amorphous silicon film is partially melted, and most of the region is in the state of solid-phase silicon. Immediately after the laser irradiation, the solid-liquid interface moves to the completely melted region immediately below the transmission region, using the solid-phase silicon immediately below the light-shielding region as a seed for crystal growth.
Super lateral to grow. As a result, large crystal grains of 1 μm or more, which are super laterally grown from the portion corresponding to the boundary between the light-shielding region and the transmission region toward the completely melted region immediately below the transmission region, are formed.

The semiconductor film may be formed such that large crystal grains grown by super lateral growth become a channel forming region.
07.

The semiconductor film is heat-treated at 300 to 450 ° C. in an atmosphere containing 3 to 100% of hydrogen, or 200 to 4% in an atmosphere containing hydrogen generated by plasma.
The remaining defects can be neutralized by the heat treatment at 50 ° C. By manufacturing an active layer of a TFT using the region 407 of the island-shaped semiconductor film manufactured as described above as a channel formation region, characteristics of the TFT can be improved.

[Second Embodiment] In the first embodiment, the transmittance of the light shielding area of the mask is 50%.
The case where the transmittance is 74% will be described. Wavelength 30
74% transmittance for 8nm XeCl excimer laser light
In this case, a single layer of a silicon nitride film 5040 of 37 nm is formed on a synthetic quartz substrate 5010 and then patterned into a desired shape.

The intensity of the laser beam passing through the light-shielding region is 74% in the light-shielding region and 93% in the transmission region, as compared with the intensity of the laser beam passing through the transmission region of the mask substrate. For example, when irradiation is performed at a laser energy density of 550 mJ / cm ^2, the laser energy densities transmitted through the light shielding area and the transmission area of the mask substrate are 407 mJ / cm ² and 51, respectively.
2 mJ / cm ² .

In this case, although the amorphous silicon film immediately below the transmission region is completely melted, it is considered that minute solid islands remain at the interface of the base immediately below the light-shielding region. Immediately after the laser irradiation, the fine solid islands are used as seeds for crystal growth, the solid-liquid interface moves around them, and super lateral growth occurs. However, if the light shielding area is large,
Many fine solid islands are formed in the light-shielding region, each of which becomes a seed for crystal growth, and grows laterally independently. If the distance between these minute solid-phase islands is too short, the crystal grains collide with each other, and sufficient super lateral growth grains cannot be obtained. In order to avoid this, it is necessary to prevent a region having a flat temperature gradient in the lateral direction (in a plane parallel to the thin film) from being formed in the semiconductor film immediately below the light-shielding region. In other words, from the center of the semiconductor film just below the light-shielding region,
It is necessary to provide an appropriate temperature gradient in a section between the light-shielding region and the semiconductor film immediately below the boundary of the transmission region. Specifically, the distance from the pattern center of the light-shielding region to the boundary between the light-shielding region and the transmission region is set to 0.5 to 4.0 μm. By doing so, fine solid islands can be formed only in the semiconductor layer corresponding to the central part of the light shielding region. As a result, in the semiconductor film, a large crystal grain region 506 of 1 μm or more, which is super laterally grown, is formed in a direction from the center of the light shielding region toward the transmission region.

FIG. 26a shows a surface SEM image of the silicon film crystallized by laser in this embodiment. The grain boundaries and the amorphous regions are etched away by the Secco etching method.
FIG. 26B illustrates a transmission region and a light shielding region corresponding to the SEM image.

As in the first embodiment, the semiconductor film is formed into an island-shaped semiconductor film 507 by removing unnecessary portions by etching so that large crystal grains grown by super lateral growth become a channel formation region.

The semiconductor film is heat-treated at 300 to 450 ° C. in an atmosphere containing 3 to 100% of hydrogen, or 200 to 4% in an atmosphere containing hydrogen generated by plasma.
The remaining defects can be neutralized by the heat treatment at 50 ° C. By manufacturing an active layer of a TFT using the region 507 of the island-shaped semiconductor film manufactured as described above as a channel formation region, characteristics of the TFT can be improved.

[Embodiment 3] Embodiment 3 is a method for forming a mask on the back surface of a sample substrate as described in claim 3. In this case, since the sample substrate itself becomes a part of the mask, it is necessary to design the mask structure in consideration of the refractive index and the attenuation constant of the sample substrate at the wavelength of the laser beam.
Such an embodiment will be described with reference to FIG. FIG.
In (A), the glass substrate described in Embodiment 1 can be suitably used for the substrate 601. In addition, the base film 602 and the amorphous semiconductor layer 603 are manufactured in the same manner as in the first embodiment.

In FIG. 6B, a laminated thin film constituting a mask is formed on the back surface of the sample substrate, and a pattern is formed in a desired shape. Silicon nitride film 60 as in the first embodiment
A laminated film of the 4a silicon oxynitride film 604b is formed so as to have a desired transmittance, a resist mask is formed by using a photolithography technique, and unnecessary portions are etched. At this time, a fluorine-based aqueous solution (for example, a mixed solution containing 7.13% of ammonium hydrogen fluoride (NH ₄ HF ₂ ) and 15.4% of ammonium fluoride (NH ₄ F) (trade name, manufactured by Stella Chemifa) LAL500)) is preferably used. Since the etching rate of the amorphous semiconductor layer 603 on the substrate surface is sufficiently smaller than that of the silicon nitride film and the silicon oxynitride film, only these insulating films forming a mask can be selectively etched.

In FIG. 6C, when laser light is incident from the back side of the sample substrate, the intensity of the laser light transmitted through the mask formed on the back surface of the sample substrate is spatially modulated, and the laser light is applied to the amorphous semiconductor film. The state of irradiation is shown.

As in the first embodiment, the semiconductor film is formed into an island-like semiconductor film 607 by removing unnecessary portions by etching so that large crystal grains grown by super lateral growth become channel forming regions.

The semiconductor film is subjected to a heat treatment at 300 to 450 ° C. in an atmosphere containing 3 to 100% hydrogen, or 200 to 4% in an atmosphere containing hydrogen generated by plasma.
The remaining defects can be neutralized by the heat treatment at 50 ° C. By manufacturing an active layer of a TFT using the region 607 of the island-shaped semiconductor film manufactured as described above as a channel formation region, characteristics of the TFT can be improved.

[Embodiment 1] FIGS. 7 to 1 show an embodiment of the present invention.
3 will be described. Here, a method for simultaneously manufacturing a pixel TFT and a storage capacitor in a pixel portion and an n-channel TFT and a p-channel TFT of a driver circuit provided in the periphery of the pixel portion will be described according to steps.

In FIG. 7A, a substrate 101 is made of a glass substrate such as barium borosilicate glass or alumino borosilicate glass typified by Corning # 7059 glass or # 1737 glass, etc. In the case where the step of conversion is performed only by laser annealing, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyether sulfone (PES)
For example, a plastic substrate having no optical anisotropy can be used. When a glass substrate is used, heat treatment may be performed in advance at a temperature lower by about 10 to 20 ° C. than the glass strain point. Then, a base film 102 such as a silicon oxide film, a silicon nitride film, or a silicon oxynitride film is formed on the surface of the substrate 101 where a TFT is to be formed, in order to prevent impurity diffusion from the substrate 101. For example, a silicon oxynitride film 102a formed from SiH ₄ , NH ₃ , and N ₂ O by a plasma CVD method is formed to a thickness of 10 to 200 nm (preferably 50 to 100 nm), and similarly, a silicon oxynitride film formed of SiH ₄ and N ₂ O. The hydrogenated silicon film 102b is
The layer is formed to a thickness of 0 nm (preferably 100 to 150 nm).

The silicon oxynitride film is a conventional parallel plate type
It is formed by a plasma CVD method. Silicon oxynitride
The film 102a is made of SiH_FourTo 10 SCCM, NH_ThreeTo 100 SCC
M, N _TwoO was introduced into the reaction chamber at 20 SCCM, and the substrate temperature was 3
25 ° C, reaction pressure 40Pa, discharge power density 0.41W / c
m^TwoAnd the discharge frequency was 60 MHz. On the other hand, hydrogen oxynitride
The silicon film 102b is made of SiH_FourTo 5 SCCM, N_TwoO to 12
0 SCCM, H_TwoInto the reaction chamber as 125 SCCM
Temperature 400 ° C, reaction pressure 20Pa, discharge power density 0.41
W / cm^TwoAnd the discharge frequency was 60 MHz. These films are
Change the temperature and change the reaction gas
It can also be done.

The silicon oxynitride film 102a is formed so that its internal stress becomes a tensile stress, considering the substrate as a center. The silicon oxynitride film 102b also has an internal stress in the same direction.
The stress should be smaller than the absolute value.

Next, 25 to 80 nm (preferably 30 to 80 nm)
Semiconductor layer 103 having a thickness of 60 nm and having an amorphous structure.
Is formed by a known method such as a plasma CVD method or a sputtering method. For example, an amorphous silicon film is formed to a thickness of 55 nm by a plasma CVD method. Semiconductor films having an amorphous structure include an amorphous semiconductor layer and a microcrystalline semiconductor film,
A compound semiconductor film having an amorphous structure such as an amorphous silicon germanium film may be used. In addition, the base film 10
2 and the amorphous semiconductor layer 103 can be formed continuously. For example, as described above, after a silicon oxynitride film 102a and a silicon oxynitride hydride film 102b are successively formed by a plasma CVD method, the reaction gas is SiH ₄ ,
By switching from N ₂ O and H ₂ to only SiH ₄ and H ₂ or only SiH ₄ , continuous formation can be achieved without once exposing it to the atmosphere. As a result, contamination at the interface between the amorphous semiconductor layer 103 and the silicon oxynitride hydrogenated film 102b can be prevented, and variation in characteristics of a TFT to be manufactured and fluctuation in threshold voltage can be reduced.

Here, a modulation mask of laser light intensity is prepared. In this example, in order to perform crystallization according to the first embodiment, a silicon nitride film, a silicon oxynitride film, a silicon nitride film, a silicon oxynitride film, and a silicon nitride film are sequentially stacked on a synthetic quartz substrate 4010. The silicon nitride film is a plasma CVD method, the reaction gas is 30 SCCM of SiH ₄ , N ₂
Was introduced into the reaction chamber at 300 SCCM and NH ₃ at 240 SCCM, and formed under the conditions of a substrate temperature of 325 ° C., a reaction pressure of 160 Pa, a discharge power density of 0.35 W / cm ² , and a discharge frequency of 13.56 MHz. The optical constant of the formed film has a refractive index of 2.1 at a wavelength of 308 nm and an attenuation constant of 0.0. The silicon oxynitride film is a plasma CVD method, the reaction gas is SiH ₄ at ₄ SCCM,
N ₂ O was introduced into the reaction chamber at 400 SCCM and H ₂ at 125 SCCM, and formed under the conditions of a substrate temperature of 400 ° C., a reaction pressure of 40 Pa, a discharge power density of 0.41 W / cm ² , and a discharge frequency of 13.56 MHz. The optical constant of the formed film has a refractive index of 1.5 and an attenuation constant of 0.0 at a wavelength of 308 nm. The thickness of each layer may be determined so as to have a desired laser light transmittance. In this embodiment, the thickness of the silicon nitride layer is set to 35 nm from the layer close to the substrate so that the transmittance of the light-shielded region becomes 30%. Membrane, 60
nm silicon oxynitride film, 35 nm silicon nitride film, 6
A 0-nm silicon oxynitride film and a 35-nm silicon nitride film were formed. And to spatially modulate the laser light,
The stacked thin film is formed into a desired island shape using a photomask and a photolithography technique. The mask manufactured as described above is arranged at an appropriate distance from the amorphous silicon film 103 as shown in FIG.
In this mask configuration, the transmittance of the transmission area is 93%, and the transmittance of the light-shielding area is 30%.

Here, the effective incident energy used in this specification is defined. That is, the energy is effectively absorbed by the silicon film and converted into heat, and is a value derived in consideration of the transmittance at the modulation mask and the reflectance at the semiconductor surface. In the case of the present embodiment, it is derived by the following equation. Effective incident energy density = Io x Tmask x (1-Rsi) Io: Irradiated laser energy density Tmask: Transmittance at mask Rsi: Reflectance at semiconductor film surface

Next, a crystallization step is performed on the amorphous silicon film 103. In the present embodiment, XeCl excimer laser light (wavelength 308 nm) was formed into a linear beam, and the entire surface of the substrate was subjected to scanning processing at an oscillation frequency of 5 to 50 Hz with an overlap ratio of the linear beam of 80 to 98%. The irradiation conditions of the laser beam are not limited to the above, and may be appropriately determined by the practitioner. However, when the energy density is normally 300 to 400 mJ / cm ² , the amorphous silicon film immediately below the transmission region is Does not completely melt (effective incident energy density of 125 to 167 mJ /
cm ² ). In this case, super lateral growth as described in the first embodiment does not occur.

For super lateral growth, an irradiation energy density of 450 to 600 mJ / cm ² (effective radiation energy density of 188 to 251 mJ immediately below the transmittance) is used to completely melt the amorphous silicon film immediately below the transmission region.
/ Cm ² ). In any of the methods of the first to third embodiments, the laser energy density of the laser light intensity passing through the light shielding area of the spatial modulation mask 401 is smaller than the laser energy density passing through the transmission area. As shown by the arrow in FIG. 7B, the laser light reaching the amorphous silicon film is not uniform in the plane.
As described above, the effective incident energy reaches the amorphous silicon film, is absorbed, and is converted into heat. Therefore, the distribution is weak under the light-shielding region of the modulation mask and high under the transmission region. The crystal growth proceeds from the boundary between the two regions in the direction of higher laser intensity.
As a result, in the regions 105 to 109, large crystal grains of 1 μm or more having crystal grain boundaries in a certain direction are obtained.
0 indicates amorphous silicon.

If the gate electrode of the TFT is formed over the region 110 where a large number of crystal defects exist, it may cause deterioration of TFT characteristics. For example, the off-current value (TFT
The current value flowing in the off state increases, or the current concentrates in this region and locally generates heat. Therefore, using a photomask and a photolithography technique, FIG.
The island-shaped semiconductor layers 111 to 115 are formed so that the region 110 is removed as shown in FIG. The shape of the island-shaped semiconductor layers 111 to 115 may be any shape as long as the super-laterally grown region becomes a channel region.

Thereafter, the island-shaped semiconductor layers 111 to 115 are formed.
And cover 5 by plasma CVD or sputtering.
A mask layer 117 of a silicon oxide film having a thickness of 0 to 100 nm is formed.

In this state, for the purpose of controlling the threshold voltage (Vth) of the TFT, an impurity element imparting p-type is added to the island-like semiconductor layer in an amount of about 1 × 10 ^{16 to} 5 × 10 ¹⁷ atoms / cm ³ . The concentration may be added to the entire surface of the island-shaped semiconductor layer. The impurity element imparting p-type to the semiconductor includes boron (B),
Elements of Group 13 of the periodic table, such as aluminum (Al) and gallium (Ga), are known. As the method, an ion implantation method or an ion doping method can be used, but the ion doping method is suitable for treating a large-area substrate.
In the ion doping method, diborane (B ₂ H ₆ ) is used as a source gas and boron (B) is added. The implantation of such an impurity element is not always necessary and may be omitted. However, it is a method preferably used for keeping the threshold voltage of the n-channel TFT within a predetermined range.

In order to form an LDD region of an n-channel TFT of a driving circuit, an impurity element imparting n-type is selectively added to the island-shaped semiconductor layers 112 and 113. Therefore, resist masks 116a to 116e are formed in advance. As the impurity element imparting n-type, phosphorus (P) or arsenic (As) may be used. Here, an ion doping method using phosphine (PH ₃ ) was applied to add phosphorus (P). The formed impurity regions are low-concentration n-type impurity regions 118 and 119, and the phosphorus (P) concentration may be in the range of 2 × 10 ^{16 to} 5 × 10 ¹⁹ atoms / cm ³ . In this specification, the concentration of the n-type impurity element included in the impurity regions 118 and 119 formed here is expressed as (n ⁻ ). Also, the impurity region 120
Is a semiconductor layer for forming a storage capacitor of a pixel matrix circuit, and phosphorus (P) is added to this region at the same concentration (FIG. 7D).

Next, the added impurity element is activated.
Perform the process. Activation is performed in a nitrogen atmosphere at 500 to 600
C. for 1 to 4 hours or by laser activation
Can be performed. It is also acceptable to use both together
No. In the case of laser activation method, KrF excimer
Form a linear beam using laser light (wavelength 248 nm)
Oscillation frequency 5-50Hz, energy density 10
0-500mJ / cm ^TwoAs linear beam overlay
The scanning is performed with the tip ratio being 80 to 98%, and the island-shaped semiconductor layer
The entire surface of the substrate on which was formed was processed. The laser light
There are no restrictions on the firing conditions, and
It should be set. At this stage, the mask layer 117 is made of hydrofluoric acid or the like.
Etching with a solution of

In FIG. 9A, a gate insulating film 123 is formed.
Is a film thickness of 4 using a plasma CVD method or a sputtering method.
The insulating film containing silicon is formed to have a thickness of 0 to 150 nm. For example, a silicon oxynitride film with a thickness of 120 nm is preferably used. In addition, a silicon oxynitride film formed by adding O ₂ to SiH ₄ and N ₂ O is a preferable material for this application because the fixed charge density in the film is reduced. Needless to say, the gate insulating film 123 is not limited to such a silicon oxynitride film, and another insulating film containing silicon may be used as a single layer or a stacked structure. In any case, the gate insulating film 123 is formed so as to have a compressive stress in consideration of the substrate.

Then, as shown in FIG. 9A, a heat-resistant conductive layer for forming a gate electrode is formed over the gate insulating film 123. The heat-resistant conductive layer may be formed as a single layer, or may be formed as a multilayer structure including a plurality of layers such as two layers or three layers as necessary. Using such a heat-resistant conductive material, for example, a conductive layer (A) 121 made of a conductive nitride metal film and a conductive layer (B) 122 made of a metal film
Are preferably laminated. The conductive layer (B) 122 is made of tantalum (Ta), titanium (Ti), molybdenum (M
o), an element selected from tungsten (W), an alloy containing the above element as a main component, or an alloy film (typically, a Mo—W alloy film or a Mo—Ta alloy film) that combines the above elements. The conductive layer (A) 121 may be formed using tantalum nitride (TaN), tungsten nitride (WN), a titanium nitride (TiN) film, molybdenum nitride (MoN), or the like. Further, as the conductive layer (A) 121, tungsten silicide, titanium silicide, or molybdenum silicide may be used. It is preferable to reduce the impurity concentration of the conductive layer (B) 122 in order to reduce the resistance. In particular, the oxygen concentration is preferably 30 ppm or less. For example, tungsten (W) has an oxygen concentration of 30 pp.
m or less, a specific resistance value of 20 μΩcm or less could be realized.

The conductive layer (A) 121 has a thickness of 10 to 50 nm (preferably 20 to 30 nm), and the conductive layer (B) 122 has a thickness of 200 to 400 nm (preferably 250 to 350 nm).
It is good. When W is used as the gate electrode, an argon (Ar) gas and a nitrogen (N ₂ ) gas are introduced by sputtering using W as a target, and the conductive layer (A) 122 is made of tungsten nitride (WN) of 50 nm. The conductive layer (B) 121 is formed with W to a thickness of 250 nm. As another method, the W film is made of tungsten hexafluoride (WF ₆ )
Can also be formed by a thermal CVD method. In any case, in order to use it as a gate electrode, it is necessary to reduce the resistance, and it is desirable that the resistivity of the W film be 20 μΩcm or less. The resistivity of the W film can be reduced by enlarging the crystal grains. However, when there are many impurity elements such as oxygen in W, crystallization is inhibited and the resistance is increased. From this, when the sputtering method is used, the purity is 99.999.
A 9% to 20 μΩcm resistivity can be achieved by using a 9% W target and further forming a W film with sufficient care so as not to mix impurities from the gas phase during film formation.

On the other hand, a TaN film is formed on the conductive layer (A) 121.
When a Ta film is used for the conductive layer (B) 122, it can be formed by a sputtering method in the same manner. TaN film is T
The target film a is formed using a mixed gas of Ar and nitrogen as a sputtering gas, and the Ta film uses Ar as a sputtering gas. When an appropriate amount of Xe or Kr is added to these sputter gases, the internal stress of the film to be formed can be relaxed and the film can be prevented from peeling. The resistivity of the α-phase Ta film is about 20 μΩcm and can be used for a gate electrode, but the resistivity of the β-phase Ta film is about 180 μΩcm and is not suitable for a gate electrode. Since the TaN film has a crystal structure close to the α-phase, an α-phase Ta film was easily obtained by forming a Ta film thereon. Although not shown, it is effective to form a silicon film doped with phosphorus (P) with a thickness of about 2 to 20 nm under the conductive layer (A) 121. Accordingly, the adhesion of the conductive film formed thereon is improved and oxidation is prevented, and at the same time, a small amount of an alkali metal element contained in the conductive layer (A) 121 or the conductive layer (B) 122 is added to the gate insulating film 123. Spreading can be prevented. In any case, the conductive layer (B) 1
22 preferably has a resistivity in the range of 10 to 50 μΩcm.

Next, using a photomask, the resist masks 124 a to 124 a to 1
24f, the conductive layer (A) 121 and the conductive layer (B) 1
22 and the gate electrodes 125 to 12
9 and the capacitance wiring 130 are formed. Gate electrodes 124-1
29 and the capacitor wiring 130 are made of a conductive layer (A) 125
a to 129a and 125b to 12 made of a conductive layer (B)
9b are integrally formed (FIG. 9B). FIG. 11C illustrates a positional relationship between the island-shaped semiconductor layer 111 and the gate electrode 125 in this state. Similarly, FIG. 12C illustrates a relationship between the island-shaped semiconductor layer 115, the gate electrode 129, and the capacitor wiring 130. FIG. 11 (C) and FIG.
In (C), the gate insulating film 123 is omitted.

The method of etching the conductive layer (A) and the conductive layer (B) may be appropriately selected by a practitioner. However, when the conductive layer (A) and the conductive layer (B) are formed of a material containing W as a main component as described above, It is desirable to apply a dry etching method using high-density plasma in order to perform etching at high speed and with high accuracy. Microwave plasma or inductively coupled plasma (Inductively Coup
It is preferable to use an led plasma (ICP) etching apparatus.
For example, in a W etching method using an ICP etching apparatus, two kinds of gases, CF ₄ and Cl ₂ , are introduced into a reaction chamber as an etching gas, and a pressure of 0.5 to 1.5 Pa (preferably 1
Pa), and a high frequency (13.56 MHz) power of 200 to 1000 W is applied to the inductive coupling portion. At this time, a high frequency power of 20 W is applied to the stage on which the substrate is placed,
By charging to a negative potential with a self-bias, positive ions are accelerated and anisotropic etching can be performed.
By using an ICP etching apparatus, even a hard metal film such as W can obtain an etching rate of 2 to 5 nm / sec. In order to perform etching without leaving a residue, overetching is preferably performed by increasing the etching time at a rate of about 10 to 20%. At this time, however, it is necessary to pay attention to the etching selectivity with the base. For example, since the selectivity of the silicon oxynitride film (gate insulating film 127) to the W film is 2.5 to 3, the exposed surface of the silicon oxynitride film is etched by about 20 to 50 nm by such an over-etching process. Has been substantially thinner.

The n-channel TFT of the pixel TFT
In order to form an LDD region, a step of adding an impurity element imparting n-type (n-doping step) was performed. Using the gate electrodes 125 to 129 as a mask, an impurity element imparting n-type in a self-aligned manner was added by an ion doping method. The concentration of phosphorus (P) added as an impurity element imparting n-type is in a concentration range of 1 × 10 ^{16 to} 5 × 10 ¹⁹ atoms / cm ³ . Thus, low-concentration n-type impurity regions 131 to 135 are formed in the island-shaped semiconductor layer as shown in FIG.

Next, in the n-channel TFT, a high-concentration n-type impurity region functioning as a source region or a drain region was formed (n ⁺ doping step). First, using a photomask, resist masks 136a to 136 are used.
d was formed, and an impurity element imparting n-type was added to form high-concentration n-type impurity regions 137 to 142. Phosphorus (P) is used as an impurity element imparting n-type, and its concentration is 1
The ion doping method using phosphine (PH ₃ ) was performed so that the concentration was in the range of × 10 ²⁰ to 1 × 10 ²¹ atoms / cm ³ (FIG. 9D).

Then, high-concentration p-type impurity regions 144 and 145 serving as a source region and a drain region are formed in the island-shaped semiconductor layers 111 and 113 forming the p-channel TFT. Here, a high concentration p-type impurity region is formed in a self-aligning manner by adding an impurity element imparting p-type using the gate electrodes 125 and 127 as a mask. At this time, the island-shaped semiconductor films 112, 114, 1 forming an n-channel TFT are formed.
Reference numeral 15 denotes a resist mask 143a using a photomask.
To 143c and cover the entire surface. The high-concentration p-type impurity regions 144 and 145 are formed by an ion doping method using diborane (B ₂ H ₆ ). The boron (B) concentration in this region is set to 3 × 10 ^{20 to} 3 × 10 ²¹ atoms / cm ³ (FIG. 10A). This high-concentration p-type impurity region 14
4 and 145, phosphorus (P) is added in the previous step, and the high concentration p-type impurity regions 144a and 145a have a concentration of 1 × 10 ²⁰ to 1 × 10 ²¹ atoms / cm ³ and a high concentration p.
Type impurity regions 144b and 145b have 1 × 10 ^{16 to} 5 ×
Although it is contained at a concentration of 10 ¹⁹ atoms / cm ³ , by increasing the concentration of boron (B) added in this step from 1.5 to 3 times, the source region and the drain of the p-channel TFT are formed. There was no problem in functioning as an area.

Thereafter, as shown in FIG. 10B, a protective insulating film 146 is formed over the gate electrode and the gate insulating film. The protective insulating film may be formed using a silicon oxide film, a silicon oxynitride film, a silicon nitride film, or a stacked film combining these. In any case, the protective insulating film 14
6 is formed from an inorganic insulating material. The thickness of the protective insulating film 146 is 100 to 200 nm. Here, when a silicon oxide film is used, tetraethyl orthosilicate (TE) is formed by a plasma CVD method.
OS) and O ₂ , a reaction pressure of 40 Pa and a substrate temperature of 3
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 00 to 400 ° C. In the case of using a silicon oxynitride film, a silicon oxynitride film formed from SiH ₄ , N ₂ O, and NH ₃ by a plasma CVD method or a silicon oxynitride film formed from SiH ₄ and N ₂ O is used. Good. The production conditions in this case are a reaction pressure of 20 to 200 Pa and a substrate temperature of 300 to 40.
0 ℃, high frequency (60MHz) power density 0.1 ~ 1.0W
/ cm ² . Also, SiH ₄ , N ₂ O,
A silicon oxynitride hydride film formed from H ₂ may be used. Similarly, a silicon nitride film can be formed from SiH ₄ and NH ₃ by a plasma CVD method. Such a protective insulating film is formed so as to have a compressive stress considering the substrate as a center.

Thereafter, a step of activating the impurity elements imparting n-type or p-type added at the respective concentrations is performed. This step is performed by a thermal annealing method using a furnace annealing furnace. In addition, a laser annealing method or a rapid thermal annealing method (RTA method) can be applied. In the thermal annealing method, the oxygen concentration is 1 ppm or less,
Preferably in a nitrogen atmosphere of 0.1 ppm or less 400 ~
The heat treatment is performed at 700 ° C, typically 500 to 600 ° C. In this embodiment, the heat treatment is performed at 550 ° C for 4 hours.
When a plastic substrate having a low heat-resistant temperature is used as the substrate 101, a laser annealing method is preferably applied (FIG. 10C).

After the activation step, an additional 3 to 100%
1 to 12 at 300 to 450 ° C. in an atmosphere containing hydrogen
A heat treatment was performed for a long time, and a step of hydrogenating the island-shaped semiconductor layer was performed. In this step, dangling bonds of 10 ¹⁶ to 10 ¹⁸ / cm ^{3 in} the island-shaped semiconductor layer are terminated by thermally excited hydrogen. Plasma hydrogenation (using hydrogen excited by plasma) as another means of hydrogenation
May be performed. The heat treatment at 300 to 450 ° C. causes the silicon oxynitride film 102
b, The island-shaped semiconductor layer may be hydrogenated by diffusing hydrogen in the silicon oxynitride film of the protective insulating film 146.

When the activation and hydrogenation steps are completed,
The interlayer insulating film 147 made of an organic insulating material is
It is formed with an average thickness of 2.0 μm. As the organic resin material, polyimide, acrylic, polyamide, polyimide amide, BCB (benzocyclobutene), or the like can be used. For example, in the case of using a polyimide that is thermally polymerized after being applied to a substrate, it is formed by firing at 300 ° C. in a clean oven. In the case of using acrylic, after using a two-pack type, mixing the main material and the curing agent, applying the entire surface of the substrate using a spinner, and preheating at 80 ° C. for 60 seconds on a hot plate. Then, it can be formed by firing in a clean oven at 250 ° C. for 60 minutes.

The surface can be satisfactorily planarized by forming the interlayer insulating film with an organic insulating material. In addition, since organic resin materials generally have a low dielectric constant, parasitic capacitance can be reduced. However, since it is hygroscopic and is not suitable as a protective film, it must be used in combination with a silicon oxide film, a silicon oxynitride film, a silicon nitride film, or the like formed as the protective insulating film 146 as in this embodiment.

After that, a resist mask having a predetermined pattern is formed using a photomask, and a contact hole reaching the source region or the drain region formed in each of the island-shaped semiconductor films is formed. The formation of the contact hole is performed by a dry etching method. In this case, an interlayer insulating film made of an organic resin material is first etched by using a mixed gas of CF ₄ , O ₂ , and He as an etching gas, and then the protective insulating film 14 is changed to CF ₄ and O ₂ as an etching gas.
6 is etched. Further, by switching the etching gas to CHF ₃ and etching the gate insulating film in order to increase the selectivity with respect to the island-shaped semiconductor layer, a contact hole can be formed favorably.

Then, a conductive metal film is formed by a sputtering method or a vacuum evaporation method, a resist mask pattern is formed by using a photomask, and the source wiring 14 is formed by etching.
8 to 152 and drain wirings 153 to 157 are formed.
The drain wiring 158 indicates a drain wiring of an adjacent pixel. Here, the drain wiring 158 functions as a pixel electrode. Although not shown, in this embodiment, this electrode is formed by forming a Ti film with a thickness of 50 to 150 nm, forming a contact with the semiconductor film forming the source or drain region of the island-shaped semiconductor layer, and forming the Ti film. Aluminum (Al) was formed in a thickness of 300 to 400 nm on the upper surface to form a wiring.

FIG. 11D is a top view of the island-shaped semiconductor layer 111, the gate electrode 125, the source wiring 148, and the drain wiring 153 in this state. Source wiring 14
Reference numeral 8 denotes an island-like semiconductor layer 11 formed by contact holes formed in an interlayer insulating film and a protective insulating film (not shown).
1 and 230 respectively. The drain wiring 153 is connected to the island-shaped semiconductor layer 111 at 231. Similarly, FIG. 12D illustrates a top view of the island-shaped semiconductor layer 115, the gate electrode 129, the capacitor wiring 130, the source wiring 152, and the drain wiring 157. Source wiring 1
52 is a contact part 234, and the drain wiring 157 is connected to the island-shaped semiconductor layer 115 by a contact part 235, respectively. In any case, a region where a large number of crystal defects are present (the region 110 under the laser light modulation mask) is removed, and an island-like semiconductor layer is formed in a region on the inner side where the super lateral growth is performed, thereby forming a TFT. .

When hydrogenation was performed in this state, favorable results were obtained for improving the characteristics of the TFT. For example, 3 ~
The heat treatment may be performed at 300 to 450 ° C. for 1 to 12 hours in an atmosphere containing 100% hydrogen, or a similar effect may be obtained by using a plasma hydrogenation method. In addition, by such a heat treatment, the protective insulating film 142 and the base film 102
Can be diffused into the island-shaped semiconductor films 111 to 115 for hydrogenation. In any case, the island-like semiconductor layer desirably in a 10 ¹⁶ / cm ³ or less the defect density in the 111 to 115, the hydrogen for the 5 × 10 ¹⁸ to 5
What should have been provided is about × 10 ¹⁹ atoms / cm ³ . In the island-shaped semiconductor layer subjected to such a treatment, the crystal grain boundaries slightly existing became inactive, and a region substantially regarded as a single crystal was formed.

Thus, the TF of the driving circuit is mounted on the same substrate.
A substrate having T and a pixel TFT in a pixel portion can be completed. The driving circuit includes a first p-channel TFT 2
00, a first n-channel TFT 201, a second p-channel TFT 202, a second n-channel TFT 20
3. In the pixel portion, a pixel TFT 204 and a storage capacitor 205 are formed. In this specification, such a substrate is referred to as an active matrix substrate for convenience.

First p-channel TFT 20 of drive circuit
0, the channel forming region 20 is formed in the island-shaped semiconductor film 111.
6. Source region 207 made of high-concentration p-type impurity region
a, 207b and a single drain structure having drain regions 208a, 208b. The first n-channel TFT 201 includes a channel formation region 209, an LDD region 210 overlapping with the gate electrode 119, a source region 212, and a drain region 211 in the island-shaped semiconductor film 112. In this LDD region, the gate electrode 115
And the length in the channel length direction is 0.5 to 3.0 μm, preferably 1.0 to 2.0 μm.
μm. By setting the length of the LDD region in the n-channel TFT in this manner, a high electric field generated in the vicinity of the drain region can be reduced, thereby preventing generation of hot carriers and preventing deterioration of the TFT. Similarly, the second p-channel type TFT 202 of the driver circuit is a single drain type in which the island-shaped semiconductor film 113 has a channel formation region 213, source regions 214a and 214b made of high-concentration p-type impurity regions, and drain regions 215a and 215b. It has a structure. In the second n-channel TFT 203, the LDD regions 217 and 21 partially overlapping the channel formation region 216 and the gate electrode 121 on the island-shaped semiconductor film 114.
8, a source region 220 and a drain region 219 are formed. The length of Lov overlapping the gate electrode of this TFT is also 0.5 to 3.0 μm, preferably 1.0 to 2.0 μm. The LDD region that does not overlap with the gate electrode is Lof.
As f, the length in the channel length direction is 0.5 to 4.0.
μm, preferably 1.0 to 2.0 μm. Pixel TF
At T204, the island-shaped semiconductor film 115 includes channel formation regions 221 and 222, LDD regions 223 to 225, and source or drain regions 226 to 228. LDD
The length of the region (Loff) in the channel length direction is 0.5 to 4.
0 μm, preferably 1.5 to 2.5 μm. Further, a storage capacitor 205 is formed from the capacitor wiring 123, an insulating film made of the same material as the gate insulating film, and a semiconductor layer 229 connected to the drain region 228 of the pixel TFT 204. In FIG. 12, the pixel TFT 204 has a double gate structure, but may have a single gate structure or a multi-gate structure provided with a plurality of gate electrodes.

FIG. 13 is a top view showing almost one pixel of the pixel portion. An AA ′ cross section in the drawing corresponds to the cross-sectional view of the pixel portion illustrated in FIG. Pixel TFT 204
The gate electrode 129 also serving as a gate wiring is formed with an island-like semiconductor layer 1 thereunder through a gate insulating film (not shown).
Intersects with 15. Although not shown, a source region, a drain region, and an LDD region are formed in the island-shaped semiconductor layer. 234 is a contact portion between the source wiring 156 and the source region 226, and 235 is a drain wiring 1
A contact portion between the drain region 57 and the drain region 228. The storage capacitor 205 is connected to the drain region 22 of the pixel TFT 204.
The capacitor wiring 130 is formed in a region where the capacitor wiring 130 overlaps with the semiconductor layer 229 extending from the gate electrode 8 via a gate insulating film.

Through the steps described above, the island-shaped semiconductor layer formed from the laser light intensity spatial modulation mask made of a material that does not absorb laser light according to the present invention has a single crystal structure. Improving the operation performance and reliability of a semiconductor device by optimizing the structure of each TFT constituting each circuit according to specifications required by a pixel TFT and a driving circuit using such an island-shaped semiconductor layer. Is possible. Furthermore, the activation of the LDD region, the source region, and the drain region is facilitated by forming the gate electrode with a conductive material having heat resistance. Then, a high-quality display device can be realized with such an active matrix substrate. A reflective liquid crystal display device can be manufactured from the active matrix substrate manufactured in this embodiment.

[Embodiment 2] In this embodiment, it is possible to produce a large grain size whose position is controlled over a wider range than in Embodiment 1, and the effect of the present invention is sufficient even when the channel region of the TFT is large. Examples of the resulting configuration are shown in FIGS.

In the process of heating and melting and cooling and solidifying the semiconductor film by laser light irradiation, a temperature distribution occurs in the lateral direction of the semiconductor layer in the sample structure in which the underlying insulating film has a stepped shape. Thus, the crystal grains can be made larger by controlling the nucleation position and the nucleation rate.

More specifically, as shown in FIG.
01 on the first insulating layers 1402 and 140
3 is provided in parallel with the channel width direction so as to sandwich the channel region A, and a second insulating layer 1404 and a semiconductor layer 1405 are formed thereon. That is, a region where the second insulating layer 1404 is formed is located below the semiconductor layer 1405 and a region where the second insulating layer 1404 is formed.
The first insulating layers 1402 and 1403 and the second insulating layer 1404
And a region where the insulating film is laminated.

The temperature distribution history when laser crystallization was performed by irradiating a pulsed laser beam to a sample structure in which such a base insulating film had a stepped shape was simulated. FIG.
The result as shown in FIG. 7 (B) was obtained.

The reason why such a result is obtained can be qualitatively explained as follows. The region B in FIG. 27A cools faster than other locations because there is both a base insulating film beside the underlying insulating film immediately below where heat escapes. Conversely, the underlying insulating film immediately below the C region
Since there is heat escaping from the region B, the temperature of the region C is hard to decrease. Therefore, a temperature gradient occurs between the region B and the region C.

Consider a case where a semiconductor film is completely melted by laser light irradiation. First, solidification starts from the semiconductor layer in the region B where the temperature decreases, and nuclei for crystal growth are generated. This nucleus becomes the center of crystal growth, and crystal growth proceeds toward the region C or region A in a high temperature and molten state. Even when the semiconductor film is not completely melted by laser light irradiation and a solid phase remains, this solid phase (minute solid phase) becomes the center of crystal growth, and super lateral growth proceeds from there using a temperature gradient. Thus, a crystal having a large grain size can be formed by controlling the position.

In FIG. 14A, a non-alkali glass substrate such as barium borosilicate glass or aluminoborosilicate glass is used as a substrate 1401. For example, # 7059 glass or # 1737 glass based on Corning Inc. can be suitably used. On the surface of the substrate 1401 where a TFT is to be formed, first insulating layers 1402 and 1403 which are transparent and have insulating properties are formed. This first insulating layer is formed using a silicon oxide film, a silicon nitride film, a silicon oxynitride film, or the like. Further, the first insulating layer may be formed of a material having excellent heat conductivity. As such a material, an oxide of aluminum (aluminum oxide (Al ₂ O ₃ ))
Is transparent to visible light and has a thermal conductivity of 20Wm-1K-
Is one. Further, aluminum oxide is not limited to the stoichiometric ratio, and other elements may be added to control characteristics such as thermal conductivity characteristics and internal stress. For example, aluminum oxynitride (AlN _x O _{1 -x} : 0.02 ≦ x ≦ 0.5) may be used by adding nitrogen to aluminum oxide, or aluminum nitride (AlN _x ) may be used. Is also possible. Alternatively, a compound containing silicon (Si), oxygen (O), nitrogen (N), and M (M is at least one selected from aluminum (Al) or a rare earth element) can be used. For example, AlSiON or L
aSiON or the like can be suitably used. In addition, boron nitride or the like can be used.

Each of the above oxides, nitrides, and compounds can be formed by a sputtering method or a plasma CVD method. In the case of the sputtering method, it can be formed by sputtering using a target having a desired composition and using an inert gas such as argon (Ar) or nitrogen. In addition, a thin diamond layer having a thermal conductivity of 1000 Wm ^-1 K ^-1 or D
An LC (Diamond Like Carbon) layer may be provided. First
The angle of the side wall at the end surface of the insulating layers 1402 and 1403 is 5 ° or more with respect to the main surface of the glass substrate 1401.
Etching is performed in a tapered shape so as to be less than 0 ° to secure a step or a coverage of a film to be laminated thereon. The size of the pair of rectangles made of the first insulating layer may be arbitrarily determined by a practitioner. Preferably, the sides of the rectangles in the channel length direction have a width of 0.5 to 2 μm.

On this, a second insulating layer 1404 is formed by silicon oxide.
Formed with capacitor film, silicon nitride film, silicon oxynitride film, etc.
To achieve. The silicon oxynitride film is formed by plasma CVD.
iH _Four, N_TwoO is used as a source gas. This source gas
To O_TwoMay be added. The production conditions are not limited,
This silicon oxynitride film as the second insulating film has a thickness of
50-500nm, oxygen concentration 55atomic% or more
Less than 70 atomic% and the nitrogen concentration is 1 atomic
% To less than 20 atomic%. like this
When the internal stress of the silicon oxynitride film decreases as a composition
In both cases, the fixed charge density is reduced. The second insulating layer is required
Although not necessary, the alkali metal is removed from the substrate 1401.
It is desirable to provide them for the purpose of preventing diffusion.

The semiconductor layer 1405 shown in FIG.
It is formed to a thickness of 25 to 80 nm (preferably 30 to 60 nm). In this method, a semiconductor film having an amorphous structure is formed by a known method such as a plasma CVD method or a sputtering method.
FIG. 14C is a top view thereof, in which the first insulating layer is formed in a stripe shape, a rectangular shape, or a strip shape. The short side of the first insulating film is provided outside the region serving as a channel so as to sandwich the region A serving as a channel of the semiconductor layer 1405 formed thereover. As the semiconductor film having an amorphous structure for forming a semiconductor layer, there are an amorphous semiconductor film and a microcrystalline semiconductor film, and a compound semiconductor film having an amorphous structure such as an amorphous silicon germanium film is used. You may. Further, the light shielding region 1406 of the laser light intensity modulation mask described in Embodiment 1 is arranged so as to surround a region used as a channel region as shown in FIG.

FIG. 15 is a diagram for explaining the laser crystallization process. Before the crystallization step, it is desirable to release hydrogen contained in the amorphous semiconductor film.
Heat treatment at 0 ° C for about 1 hour to reduce hydrogen content to 5at
It is good to keep it below om%. Laser irradiation was performed under the same conditions as in Example 1.

FIG. 15A shows a state in which a semiconductor layer is irradiated with a laser beam 1508. Here, the laser modulation mask is omitted. In FIG. 15C, first insulating layers 1502 and 1503 and regions A and B, and
The positional relationship of the light shielding area 1508 of the laser modulation mask is shown when viewed from above the substrate. In the figure, the direction of crystal growth is also indicated by arrows. Improving the characteristics of TFTs by preparing two preferential nucleation layers: a method in which a nucleus generation site is a modulation boundary part by laser light modulation and a method in which a nucleus generation site is a step part due to a base step. Can be. [Embodiment 3] In this embodiment, as in Embodiment 2, Embodiment 1
FIG. 16 shows a configuration example in which a large grain size whose position is controlled over a wider range can be manufactured as compared with that of FIG.

In the process of heating and melting and cooling and solidifying a semiconductor film by laser light irradiation, in a sample structure having a low thermal conductivity base film, the heat flow from the semiconductor film immediately above the low thermal conductivity base film to the substrate side may be reduced. it can. That is,
The cooling rate of the semiconductor layer 1605 immediately above the low thermal conductivity base film 1602 is reduced, and the melting time after laser irradiation can be extended. This can be used to extend the distance of super lateral growth. Specifically, FIG.
As shown in the figure, the organic resin film 1602 is formed in an island shape between the substrate 1601 and the inorganic insulating film 1603, and the island-shaped organic resin film 1602 is formed within a region A which is a channel region of the semiconductor film 1604. Formed.

When this structure is irradiated with laser light, the laser light is absorbed by the semiconductor film 1604 and converted into heat. This heat is diffused in the direction of the substrate 1601. After standing for a certain period of time after stopping the laser irradiation, the semiconductor film starts to solidify from a molten state. At this time, since the island-shaped organic resin film 1602 is formed below the region A, heat diffusion from the semiconductor film 1604 to the substrate 1601 is suppressed as compared with the region B, and the cooling rate is reduced. Therefore, as compared with the region B, in the region A, it is possible to lengthen the time from the stop of the laser irradiation until the solidification starts. Therefore, by controlling the lateral growth direction from the region B to the region A, the super lateral growth distance can be more effectively extended.

The organic resin film 1602 is formed on the substrate by T
The FT is formed in an island shape in accordance with the arrangement of an active layer (a semiconductor film in which a channel formation region, a source region, a drain region, and an LDD region are formed). The organic resin film has a thermal conductivity of 1.0 Wm ^-1 K ^-1 or less, preferably 0.1 Wm ^-1 K ^-1 .
There is no particular limitation as long as it is 3 Wm ^-1 K ^-1 or less. The thermal conductivity of this organic resin film 1602 depends on the substrate (quartz glass: 1.
4 Wm ^-1 K ^-1 ) and the silicon-containing inorganic insulating film (1-2 Wm ^-1 K ^-1 ) which is in contact with the organic resin film, so that thermal diffusion from the semiconductor film to the substrate is sufficiently suppressed. Can be

For example, as the organic resin film 1602,
BCB (benzocyclobutene) resin, polyimide resin (fluorinated polyimide), acrylic resin, siloxane resin, fluorinated paraxylene, fluorinated parylene, teflon, fluoropolyallyl ether, PFC
B, polysilazane and the like. Above all, heat resistance is 4
BCB (benzocyclobutene) resin which is as high as about 50 ° C., has plasma resistance, and has flatness is most preferable in the present invention.

The organic resin film 1602 has an inorganic insulating film 1
In order to stack 603, an amorphous semiconductor film, and the like, it is preferable to form the surface by a spin coating method in which the surface becomes flat.
It is desirable that the edge of the patterned organic resin film has a tapered shape so that the coverage is good.
In addition, when an organic resin film is formed using a coating method typified by a spin coating method, the cost is significantly lower than that of an inorganic insulating film using a CVD apparatus, which is advantageous because a complicated film formation process is not required. is there. In addition, if a photosensitive organic resin film is used also in the pattern processing, the number of steps can be reduced because photolithography using a photoresist is not required. In addition, even when a photosensitive organic resin film is not used, the etching rate with the substrate or the base insulating film can be easily secured and the controllability is high as compared with the case of etching the inorganic insulating film, which is advantageous.

The thickness of the organic resin film is 100 nm to 100 nm.
It is desirable to set it to 500 nm. By adjusting the film thickness, the cooling rate in the crystallization step can be controlled. When the thickness is smaller than 100 nm, the flatness is deteriorated. If the thickness is larger than 500 nm, the step is too large, and it becomes difficult to form a laminated film.

Further, as the inorganic insulating film containing silicon, P
A single-layer film selected from a silicon oxide film, a silicon nitride film, and a silicon oxynitride film by a CVD method, an LPCVD method, or a sputtering method, or a stacked film thereof can be used as appropriate. The inorganic insulating film has a role of preventing impurity diffusion from the substrate and the organic resin film, and a role of improving adhesion to a stacked semiconductor film. A substrate covered with a silicon oxide film using BCB resin (450 ° C.) as an organic resin film can withstand heat treatment at about 550 ° C.
As described above, the inorganic insulating film has a function of protecting the organic resin film and has an effect of improving the heat resistance of the organic resin film.

The thickness of the inorganic insulating film containing silicon is set to 50 nm to 200 nm. When the thickness of the inorganic insulating film is greater than 200 nm, the heat capacity of the inorganic insulating film itself increases, and the effect of spatial control of heat diffusion due to the presence of the organic resin film tends to be lost. Further, when the thickness of the inorganic insulating film is smaller than 50 nm, the coverage is deteriorated and the organic resin film may not be covered.

[0097] Examples of the semiconductor film having an amorphous structure formed on an inorganic insulating film containing silicon include an amorphous semiconductor film and a microcrystalline semiconductor film, and an amorphous silicon germanium film and the like. A compound semiconductor film having a structure may be used. Further, the method of forming the amorphous semiconductor film is PCVD.
A known method such as a sputtering method, an LPCVD method, or a sputtering method may be used.

Referring to FIG. 16, the step of laser crystallization in this embodiment will be described. It is desirable to release hydrogen contained in the amorphous semiconductor film before the crystallization step. The conditions for hydrogen release and laser irradiation were the same as in Examples 1 and 2.

First, an organic resin film is formed on a substrate 1601 made of a non-alkali glass substrate or the like, and is patterned to form an organic resin film 1602 having a desired shape (island shape). (FIG. 16A)

Next, an inorganic insulating film 1603 covering the organic resin film 1602 is formed. Subsequently, the inorganic insulating film 1603
An amorphous semiconductor film 1604 is formed thereover. Here, the inorganic insulating film 1603 and the amorphous semiconductor film 1 are not exposed to the air.
604 is preferably formed continuously to reduce contamination of impurities.

Next, laser light (arrow in FIG. 16A)
To crystallize the amorphous semiconductor film to form a crystalline semiconductor film. However, the laser light intensity modulation mask is omitted in this figure. The laser light intensity modulation mask described in the first embodiment is used. FIG. 16C shows the organic resin film 1602 and the light shielding region 16 of the laser light intensity modulation mask.
The position relationship of 07 is seen from the upper surface of the substrate. In the figure, the direction of crystal growth is also indicated by arrows. The crystal grows in a super lateral direction from a portion corresponding to a boundary between the light-shielding region and the transmission region toward a completely molten region immediately below the transmission region. In the case of this embodiment, the semiconductor film immediately above the low thermal conductivity base film has a long melting time. Therefore, the super lateral growth distance can be extended. By the laser crystallization according to this configuration, it is possible to produce a large grain size whose position is controlled over a wide range.

Next, the crystalline semiconductor film is patterned to complete an island-shaped crystalline semiconductor film composed of regions A and B.

The island-shaped crystalline semiconductor film formed as described above is used as an active layer (channel forming region, source region,
If a TFT is manufactured in accordance with a known method using a semiconductor film in which a drain region and an LDD region are formed,
A semiconductor device having excellent electric characteristics can be obtained.

[Embodiment 4] The active matrix substrate manufactured in Embodiment 1 can be applied to a reflection type liquid crystal display device as it is. On the other hand, in the case of a transmissive liquid crystal display device, a pixel electrode provided for each pixel in the pixel portion may be formed of a transparent electrode. In this embodiment, a method for manufacturing an active matrix substrate corresponding to a transmission type liquid crystal display device will be described with reference to FIGS.

The active matrix substrate is manufactured in the same manner as in the first embodiment. In FIG. 17A, a conductive metal film is formed for a source wiring and a drain wiring by a sputtering method or a vacuum evaporation method. In this method, a Ti film is formed to a thickness of 50 to 150 nm, a contact is formed with a semiconductor film forming a source or drain region of an island-shaped semiconductor layer, and aluminum (Al) is formed on the Ti film by a thickness of 300 to 150 nm. It is formed to a thickness of 400 nm, and a Ti film or a titanium nitride (TiN) film is
It was formed to a thickness of 00 to 200 nm to form a three-layer structure. After that, a transparent conductive film is formed over the entire surface, and a pixel electrode 171 is formed by a patterning process using a photomask and an etching process. The pixel electrode 160 is formed on the interlayer insulating film 14.
7 and the drain wiring 15 of the pixel TFT 204.
9 is provided to form a connection structure.

In FIG. 17B, first, an interlayer insulating film 147 is formed.
This is an example in which a transparent conductive film is formed thereon, a patterning process and an etching process are performed to form a pixel electrode 160, and then a drain wiring 161 is formed by providing a portion overlapping with the pixel electrode 162. The drain wiring 161 has a thickness of 50 to
A contact is formed with a semiconductor film forming a source or drain region of an island-shaped semiconductor layer, and aluminum (Al) is formed on the Ti film so as to have a thickness of 30 nm.
It is formed and provided with a thickness of 0 to 400 nm. With this configuration, the pixel electrode 162 is connected to the T
It comes into contact with only the i film. As a result, FIG.
The reaction between the transparent conductive film material and Al can be reliably prevented as compared with the configuration of (A).

The material of the transparent conductive film is indium oxide (I
n ₂ O ₃ ) and indium tin oxide alloy (In ₂ O ₃ —S
nO ₂ ; ITO) or the like can be formed by a sputtering method, a vacuum evaporation method, or the like. The etching of such a material is performed using a hydrochloric acid-based solution. However, in particular, since etching of ITO easily generates residues, an indium oxide-zinc oxide alloy (In ₂ O ₃ —ZnO) may be used to improve the etching processability. Since the indium oxide zinc oxide alloy has excellent surface smoothness and excellent thermal stability with respect to ITO, it is possible to prevent a corrosion reaction with Al in contact with the end face of the drain wiring 159 in the structure of FIG. . Similarly, zinc oxide (ZnO) is also a suitable material, and zinc oxide (ZnO :) to which gallium (Ga) is added to increase the transmittance and conductivity of visible light.
Ga) can be used.

Thus, an active matrix substrate corresponding to a transmission type liquid crystal display device can be completed. In the present embodiment, steps similar to those in the first embodiment have been described. However, such a configuration can be applied to the active matrix substrates described in the second and third embodiments.

[Embodiment 5] In this embodiment, a process of manufacturing an active matrix type liquid crystal display device from the active matrix substrate manufactured in Embodiment 1 will be described. First,
As shown in FIG. 18A, a spacer including a columnar spacer 164 is formed on the active matrix substrate in the state shown in FIG. The spacer may be provided by scattering particles of several μm, but here, a method of forming a resin film over the entire surface of the substrate and then patterning the resin film is adopted. Although there is no limitation on the material of such a spacer, for example, NN700 manufactured by JSR Corporation is applied by a spinner and then formed into a predetermined pattern by exposure and development processing. Further, it is cured by heating at 150 to 200 ° C. in a clean oven or the like. The shape of the spacer manufactured in this manner can be varied depending on the conditions of the exposure and development treatments. Preferably, the shape of the columnar spacer 164 is columnar and the top is flat, so that When the substrates are combined, the mechanical strength of the liquid crystal display panel can be secured. The shape is not particularly limited, such as a conical shape or a pyramid shape. For example, when the shape is a conical shape, specifically, the height H is set to 1.2 to 5 μm, and the average radius L1 is set.
Is 5 to 7 μm, and the ratio between the average radius L1 and the bottom radius L2 is 1: 1.5. At this time, the taper angle of the side surface is ± 15
° or less.

The arrangement of the columnar spacers may be determined arbitrarily, but preferably, as shown in FIG. 18A, in the pixel portion, the portion overlaps with the contact portion 235 of the drain wiring 157 (pixel electrode). It is preferable to form the columnar spacer 164 so as to cover it. Since the flatness of the contact portion 235 is impaired and the liquid crystal is not well aligned in this portion, the columnar spacer 148 is formed in such a manner that the contact portion 235 is filled with the resin for the spacer, so that disclination and the like can be performed. Can be prevented.

After that, an alignment film 165 is formed. Usually, a polyimide resin is used for the alignment film of the liquid crystal display element. After forming the alignment film, a rubbing treatment was performed so that the liquid crystal molecules were aligned with a certain pretilt angle. The area not rubbed in the rubbing direction from the end of the columnar spacer 164 provided in the pixel portion was set to 2 μm or less. In the rubbing treatment, the generation of static electricity often poses a problem. However, the spacer 163 is provided on the TFT of the driving circuit and at least on the source wiring and the drain wiring.
By forming a to 163e, the original role as a spacer in the rubbing step and the effect of protecting the TFT from static electricity can be obtained.

The opposing substrate 166 on the opposing side has a light shielding film 16
7. A transparent conductive film 168 and an alignment film 169 are formed.
The light shielding film 167 is made of Ti, Cr, Al, etc.
It is formed with a thickness of nm. Then, the active matrix substrate on which the pixel portion and the driver circuit are formed and the counter substrate are bonded with a sealant 170. A filler 171 is mixed in the sealant 170, and the two substrates are bonded at a uniform interval by the filler 171 and the spacers 163 and 164. Thereafter, a liquid crystal material 172 is injected between the two substrates, and completely sealed with a sealing agent (not shown). A known liquid crystal material may be used as the liquid crystal material.
For example, in addition to the TN liquid crystal, a thresholdless antiferroelectric mixed liquid crystal exhibiting electro-optical response in which the transmittance continuously changes with respect to an electric field can be used. Some of the thresholdless antiferroelectric mixed liquid crystals exhibit a V-shaped electro-optical response characteristic. Thus, the active matrix liquid crystal display device shown in FIG. 18B is completed.

In FIG. 18, the spacer 163 is connected to the T of the driving circuit.
The spacers 163a to 163e are also formed on at least the source wiring and the drain wiring on the FT.
In addition, the driving circuit may be formed so as to cover the entire surface.

FIG. 19 is a top view of the active matrix substrate, showing a positional relationship between the pixel portion and the drive circuit portion, the spacers, and the sealant. Pixel unit 1900
, A scanning signal driving circuit 1901 and an image signal driving circuit 1902 are provided as driving circuits. Further, a signal processing circuit 1903 such as a CPU and a memory may be added. These drive circuits are connected to an external input / output terminal 1910 by a connection wiring 1911. In the pixel portion 1900, the scanning signal driving circuit 1901
And a source wiring group 1905 extending from the image signal driving circuit 1902 intersect in a matrix to form pixels, and each pixel is provided with a pixel TFT 204 and a storage capacitor 205. .

Columnar spacer 1 provided in pixel section
Reference numeral 906 corresponds to the columnar spacer 164 shown in FIG. 18, and may be provided for all pixels, or may be provided every few to tens of pixels arranged in a matrix. That is, the ratio of the number of spacers to the total number of pixels constituting the pixel portion is preferably 20 to 100%. Further, spacers 1907 and 1908 provided in the driving circuit portion,
1909 may be provided so as to cover the entire surface.
As shown at 8, each TFT may be divided into a plurality of portions in accordance with the positions of the source and drain wirings.

The sealant 170 is formed outside the pixel portion 1900, the scanning signal control circuit 1901, the image signal control circuit 1902, and other signal processing circuits 1903 on the substrate 101 and inside the external input / output terminal 1910. I do.

The configuration of such an active matrix type liquid crystal display device will be described with reference to the perspective view of FIG. FIG.
0, the active matrix substrate is a glass substrate 1
01, a pixel portion 1900, a scanning signal driving circuit 1901, an image signal driving circuit 1902, and another signal processing circuit 1903. Pixel unit 1900
Is provided with a pixel TFT 204 and a storage capacitor 205, and a driving circuit provided around the pixel portion is basically configured by a CMOS circuit. A scanning signal driving circuit 1901;
Each of the image signal driving circuits 1902 has a gate wiring 129.
And the source wiring 152 is connected to the pixel TFT 204. In addition, Flexible Printed Wiring Board (Flexible Pri
nted Circuit (FPC) 2002 is the external input terminal 191
0 and used to input image signals and the like.
Flexible printed wiring board 2002 is made of reinforcing resin 200
1, the adhesive strength is increased and fixed. Then, a connection wiring 1911 is connected to each drive circuit. Also,
Although not shown, the opposing substrate 173 is provided with a light-shielding film and a transparent electrode.

The liquid crystal display device having such a configuration can be formed using the active matrix substrates shown in the first to fourth embodiments. For example, a reflective liquid crystal display device can be obtained by using the active matrix substrates described in Embodiments 1 to 3, and a transmission liquid crystal display device can be obtained by using the active matrix substrate described in Embodiment 4.

[Embodiment 6] In this embodiment, an example in which the present invention is applied to a display device (organic EL display device) using an active matrix type organic electroluminescence (organic EL) material will be described with reference to FIG. FIG. 21A is a circuit diagram of an active matrix organic EL display device in which a display region is provided on a glass substrate and a driving circuit is provided around the display region. This organic EL display device has a display area 1 provided on a substrate.
1. X-direction peripheral drive circuit 12, Y-direction peripheral drive circuit 13
Consists of This display area 11 is used for the switching TFT 3.
0, storage capacitor 32, current controlling TFT 31, organic EL element 33, X-direction signal lines 18a, 18b, power supply line 19a,
19b, Y direction signal lines 20a, 20b, 20c and the like.

FIG. 21B is a top view of substantially one pixel. The switching TFT 30 is preferably formed in the same manner as the n-channel TFT 204 shown in FIG. 10C, and the current controlling TFT 31 is preferably formed in the same manner as the n-channel TFT 201.

FIG. 22 is a cross-sectional view taken along the line BB ′ in FIG. 21B, and shows a cross-sectional view of the switching TFT 30, the storage capacitor 32, the current controlling TFT 31, and the organic EL element portion. In FIG. 22, the island-shaped semiconductor layers 43 and 44 are manufactured by the method of the first to third embodiments. Then, the base films 41 and 42, the gate insulating film 45, and the protective insulating film 4 are formed on the substrate 40.
6, the gate electrodes 47 and 48, the capacitance wiring 49, the source and drain wirings 18a, 19a, 51 and 52, and the interlayer insulating film 50 are manufactured in the same manner as in the first embodiment. Then, the second interlayer insulating film 5 is formed thereon similarly to the interlayer insulating film 50.
After forming a contact hole reaching the drain wiring 52, the pixel electrode 5 made of a transparent conductive film is formed.
4 is formed. The organic EL element section includes an organic EL layer 55 formed over the pixel electrode 54, the pixel electrode and the second interlayer insulating film 53, and a MgAg layer formed thereon.
The first electrode 56 made of a compound and the second electrode 57 made of Al are formed. Although not shown, color display can be performed by providing a color filter. In any case, an active matrix organic EL display device can be easily manufactured by applying the method of manufacturing an active matrix substrate described in Embodiments 1 to 3.

[Embodiment 7] An active matrix substrate, a liquid crystal display device, and an E manufactured according to the present invention are manufactured.
The L-type display device can be used for various electro-optical devices. The present invention can be applied to all electronic devices incorporating such an electro-optical device as a display medium. Examples of the electronic device include a personal computer, a digital camera, a video camera, a portable information terminal (a mobile computer, a mobile phone, an electronic book, and the like), a navigation system, and the like.

FIG. 23A shows a portable information terminal, which comprises a main body 2201, an image input section 2202, an image receiving section 2203, operation switches 2204, and a display device 2205. The present invention can be applied to the display device 2205 and other signal control circuits.

Such a portable information terminal is often used not only indoors but also outdoors. In order to enable long-term use, no backlight is used, and a reflective liquid crystal display device that uses external light is suitable as a low-power-consumption type, but a backlight is provided when the surroundings are dark. A transmissive liquid crystal display device is suitable. Against this background, a hybrid type liquid crystal display device having both the reflection type and the transmission type features has been developed, but the present invention can also be applied to such a hybrid type liquid crystal display device. The display device 2205 includes a touch panel 3002 and a liquid crystal display device 300.
3. It is composed of an LED backlight 3004. The touch panel 3002 is provided to simplify the operation of the portable information terminal. In the configuration of the touch panel 3002, a light emitting element 3100 such as an LED is provided at one end, and a light receiving element 3200 such as a photodiode is provided at the other end, and an optical path is formed between the two. When the optical path is interrupted by pressing the touch panel 3002, the light receiving element 3200
Since the output of the light-emitting element changes, the light-emitting element and the light-receiving element are arranged in a matrix on the liquid crystal display device using this principle, so that the element can function as an input medium.

FIG. 23B shows a structure of a pixel portion of a hybrid liquid crystal display device, in which a drain wiring 177 and a pixel electrode 178 are provided on an interlayer insulating film over a pixel TFT 204 and a storage capacitor 205. Such a configuration,
It can be formed by applying the fourth embodiment. The drain wiring has a laminated structure of a Ti film and an Al film and also serves as a pixel electrode. The pixel electrode 177 is formed using the transparent conductive film material described in Embodiment 4. Liquid crystal display device 30
03 can be suitably used for a portable information terminal by being manufactured from such an active matrix substrate.

FIG. 24A shows a personal computer, which comprises a main body 2001 provided with a microprocessor and a memory, an image input unit 2002, a display device 2003, and a keyboard 2004. The present invention relates to a display device 20.
03 and other signal processing circuits can be formed.

FIG. 24B shows a video camera, which includes a main body 2101, a display device 2102, an audio input unit 2103, an operation switch 2104, a battery 2105, and an image receiving unit 21.
06. The present invention can be applied to the display device 2102 and other signal control circuits.

FIG. 24B shows a goggle type display, which comprises a main body 2901, a display device 2902, and an arm 29.
It consists of 03. The present invention can be applied to the display device 2902 and other signal control circuits (not shown).

FIG. 24D shows an electronic game machine such as a video game or a video game. A main body 23 on which an electronic circuit 2308 such as a CPU and a recording medium 2304 are mounted is shown.
01, a controller 2305, a display device 2303, and a display device 2302 incorporated in the main body 2301. The display device 2303 and the display device 2302 incorporated in the main body 2301 may display the same information, or display information on the recording medium 2304 using the former as a main display device and the latter as a sub-display device. The operation state can be displayed or a touch panel function can be added to form an operation panel. Further, the main body 2301, the controller 2305, and the display device 2303 may be wired communication to transmit signals to each other, or the sensor unit 2306,
2307 may be provided for wireless communication or optical communication.
The present invention can be applied to the display devices 2302 and 2303. The display device 2303 can use a conventional CRT.

FIG. 24D shows a player that uses a recording medium (hereinafter, referred to as a recording medium) on which a program is recorded, and includes a main body 2401, a display device 2402, and a speaker unit 2.
403, a recording medium 2404, and operation switches 2405. The recording medium is a DVD (Digital Versati
le Disc) and compact disc (CD).
Playback of music programs, video display, video games (or video games), information display via the Internet, and the like can be performed. The present invention can be suitably used for the display device 2402 and other signal control circuits.

FIG. 24E shows a digital camera, which comprises a main body 2501, a display device 2502, an eyepiece section 2503, operation switches 2504, and an image receiving section (not shown). The present invention can be applied to the display device 2502 and other signal control circuits.

FIG. 25A shows a front type projector, which comprises a light source optical system, a display device 2601, and a screen 2602. The present invention can be applied to a display device and other signal control circuits. FIG. 25B illustrates a rear projector, which includes a main body 2701, a light source optical system and a display device 2702, a mirror 2703, and a screen 2704. The present invention can be applied to a display device and other signal control circuits.

FIG. 25C shows the light source optical system and the display device 26 shown in FIGS. 25A and 25B.
01 and 2702 are shown as examples. A light source optical system and display devices 2601 and 2702 include a light source optical system 2801, mirrors 2802 and 2804 to 2806, a dichroic mirror 2803, a beam splitter 2807, a liquid crystal display device 2808, a phase difference plate 2809, and a projection optical system 2810.
It consists of. The projection optical system 2810 includes a plurality of optical lenses. FIG. 25C illustrates a liquid crystal display device 2808.
Although an example of a three-plate system using three is shown, the invention is not limited to such a system, and a single-plate optical system may be used. An optical path indicated by an arrow in FIG. 25C may be provided with a suitable optical lens, a film having a polarizing function, a film for adjusting a phase, an IR film, or the like. FIG. 25D shows the light source optical system 2 shown in FIG.
801 is a diagram showing an example of the structure of FIG. In this embodiment,
The light source optical system 2801 includes a reflector 2811 and a light source 28.
12, a lens array 2813, 2814, a polarization conversion element 2815, and a condenser lens 2816. FIG.
The light source optical system shown in FIG. 5D is an example, and is not limited to the illustrated configuration.

Although not shown here, the present invention can also be applied to a navigation system, a reading circuit of an image sensor, and the like. As described above, the applicable range of the present invention is extremely wide, and the present invention can be applied to electronic devices in all fields. Further, the electronic apparatus of the present embodiment can be realized by using the techniques of Embodiments 1 to 4.

[0135]

By using the technique of the laser crystallization method of the present invention, large crystal grains whose position is controlled can be produced. By forming the positions of the crystal grains of the crystalline semiconductor film in accordance with the channel formation region of the TFT, the static characteristics and dynamic characteristics of the TFT can be remarkably improved.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a relationship between a configuration of a laminated light-shielding mask and transmittance, for explaining the present invention.

FIG. 2 is a diagram illustrating the relationship between the configuration of a single-layer light-shielding mask and transmittance, for explaining the present invention.

FIG. 3 illustrates the crystal growth direction when laser crystallization is performed by spatially modulating the intensity distribution of laser light, which explains the present invention.

FIG. 4 illustrates a manufacturing process of an island-shaped semiconductor layer of the present invention.

FIG. 5 illustrates a manufacturing process of an island-shaped semiconductor layer of the present invention.

FIG. 6 illustrates a step of manufacturing an island-shaped semiconductor layer of the present invention.

FIG. 7 is a cross-sectional view illustrating a manufacturing process of a pixel TFT and a TFT of a driver circuit.

FIG. 8 is a cross-sectional view illustrating a manufacturing process of a pixel TFT and a TFT of a driver circuit.

FIG. 9 is a cross-sectional view illustrating a manufacturing process of a pixel TFT and a TFT of a driver circuit.

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

FIG. 11 is a top view illustrating a manufacturing process of a TFT of a driver circuit.

FIG. 12 is a top view illustrating a manufacturing process of a pixel TFT.

FIG. 13 is a top view illustrating pixels in a pixel portion.

FIG. 14 illustrates a structure for manufacturing a semiconductor layer.

FIG. 15 illustrates a manufacturing process of an island-shaped semiconductor layer.

FIG. 16 illustrates a manufacturing process of a semiconductor layer.

FIG. 17 is a cross-sectional view illustrating a manufacturing process of a pixel TFT and a TFT of a driver circuit.

FIG. 18 is a cross-sectional view illustrating a manufacturing process of an active matrix liquid crystal display device.

FIG. 19 is a top view illustrating input / output terminals, wiring, circuit arrangement, spacers, and sealants of a liquid crystal display device.

FIG. 20 is a perspective view illustrating a structure of a liquid crystal display device.

FIG. 21 illustrates a structure of an active matrix EL display device.

FIG. 22 is a cross-sectional view illustrating a structure of a pixel portion of an active matrix EL display device.

FIG 23 illustrates an example of a semiconductor device.

FIG 24 illustrates an example of a semiconductor device.

FIG. 25 illustrates a configuration of a projection type liquid crystal display device.

FIG. 26 is a diagram showing a result of SEM observation of a grain boundary state according to the second embodiment.

FIG. 27 is a diagram showing a temperature distribution simulation result by an underlayer step structure in the second embodiment.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) H01L 21/336 H01L 29/78 627G

Claims (13)

[Claims] A step of forming a base film in close contact with one main surface of a substrate; a step of forming a semiconductor thin film layer on the base film; A laser crystallization step of forming a semiconductor layer having: and a method of manufacturing a semiconductor device provided with a thin film transistor using the semiconductor layer as an active layer, wherein the laser crystallization step is performed via a mask that changes the transmittance of laser light. Spatially modulates the intensity, and
A method for manufacturing a semiconductor device, wherein laser light is not absorbed by the mask. 2. A method for manufacturing a semiconductor device, wherein the mask is formed on a substrate that transmits laser light. 3. A method for manufacturing a semiconductor device, wherein the mask is formed on a surface of a substrate opposite to one main surface of the substrate. 4. A method for manufacturing a semiconductor device, wherein a material of a film forming the mask has an attenuation constant at a wavelength of laser light of 0.0 to 0.1. 5. The mask according to claim 1, wherein the mask comprises a laser light transmitting area and a light shielding area, and the energy intensity of the laser light passing through the light shielding area is 0 to 90% of the energy intensity of the laser light passing through the transparent area. A method for manufacturing a semiconductor device. 6. The method of manufacturing a semiconductor device according to claim 1, wherein the mask comprises a laser light transmitting region and a light shielding region, and the laser light absorptance is 20% or less in any of the regions. 7. A method for manufacturing a semiconductor device, wherein the mask is constituted by a single layer or a multilayer film, and each layer uses a film selected from the group consisting of a silicon oxide film, a silicon nitride film, and silicon nitride oxide. Method. 8. The semiconductor device according to claim 1, wherein the base film has a projection having an uneven shape at a predetermined position, and the semiconductor film is formed continuously over a step region from a concave region to a convex region. A semiconductor device characterized by the above-mentioned. 9. The semiconductor device according to claim 1, wherein said base film is composed of an organic resin film formed in an island shape at a predetermined position, and an inorganic insulating film covering said organic resin film. . 10. The semiconductor device according to claim 9, wherein said organic resin film has a thermal conductivity of 1.0 Wm ^-1 K ^-1 or less. 11. The semiconductor device according to claim 9, wherein said organic resin film has photosensitivity. 12. The organic resin film according to claim 9, wherein said organic resin film is made of BCB (benzocyclobutene).
A single-layer film selected from a resin, a polyimide-based resin (fluorine-added polyimide), an acrylic resin, a siloxane-based resin, a fluorine-containing paraxylene, a fluorine-containing parylene, Teflon (registered trademark), fluoropolyallyl ether, PFCB, and polysilazane; Alternatively, a semiconductor device which is a stacked film thereof. 13. The semiconductor device according to claim 1, wherein the semiconductor device is a display device using an organic electroluminescent material, a personal computer, a video camera, a portable information terminal, a digital camera,
A method for manufacturing a semiconductor device, which is a digital video disk player, a goggle type display, an electronic game machine, or a projector.