JP2006032924A - Method of manufacturing semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To control the crystal lateral growth position of a semiconductor film without complicating the device. <P>SOLUTION: An insulating substrate is overlaid with a semiconductor film, and a part of the semiconductor film with a reflective film comprising an insulating film. By irradiating with laser beam with the reflective film as a mask, the exposed semiconductor film is crystallized. Moreover, the reflective film is an interlaminated structure of the insulating films with a high refractive index and the insulating films with a low refractive index in the constitution of the invention. Concretely, the reflective film comprises a silicon oxide film and a silicon nitride film formed on the silicon oxide film in contact with it. The reflective film is more preferably laminated of the silicon oxide films and the silicon nitride films in several layers. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a semiconductor device. In particular, a semiconductor film formed on an insulating substrate is laterally crystallized by irradiation with laser light, and a thin film transistor formed using the laterally crystallized semiconductor film (hereinafter referred to as “TFT” in this specification). The present invention relates to a method for manufacturing a semiconductor device having the following.

  In recent years, a technique for crystallizing or improving crystallinity by laser annealing a semiconductor film (particularly an amorphous semiconductor film) formed over an insulating substrate such as glass has been widely studied. Silicon is often used as the semiconductor film.

  Compared with a synthetic quartz glass substrate that has been widely used in the past, a glass substrate is inexpensive and rich in workability, and has an advantage that a large-area substrate can be easily manufactured. On the other hand, since the glass substrate has a lower melting point than the synthetic quartz glass substrate, there is a drawback that it cannot be heated so much in the step of crystallizing the semiconductor film formed on the substrate. Therefore, as a method for forming a semiconductor film on a glass substrate and crystallizing the semiconductor film, a method using a laser is frequently used. This is because the laser can give high energy only to the amorphous semiconductor film without excessively increasing the temperature of the substrate.

  A crystalline semiconductor film formed by laser annealing has high mobility. For this reason, a TFT is formed using this crystalline semiconductor film, and it is actively used for a monolithic liquid crystal electro-optical device or the like in which a TFT for a pixel portion and a driver circuit are formed on a single glass substrate. .

  In addition, a pulse oscillation type laser beam such as an excimer laser is processed by an optical system so that a square spot of several centimeters square or a linear shape of 10 cm or more in length is irradiated on the surface to be irradiated. A method of performing laser annealing by relatively scanning a surface with a laser beam is widely used because it is highly productive and industrially excellent.

  In particular, when a linear beam is used, the entire surface to be irradiated is scanned by scanning only in a direction perpendicular to the longitudinal direction of the linear beam, unlike the case of using a spot laser beam that requires scanning in the front, rear, left, and right directions. Productivity is high because the beam can be irradiated. The reason for scanning in the direction perpendicular to the longitudinal direction is that it is the most efficient scanning direction. Due to this high productivity, in the current laser annealing method, the use of a linear beam obtained by processing a laser beam of a pulsed excimer laser with an appropriate optical system has become the mainstream of manufacturing technology for liquid crystal display devices using TFTs. It is becoming. In addition, by this technique, a monolithic liquid crystal display device in which a TFT (pixel TFT) that forms a pixel portion on one glass substrate and a TFT of a driving circuit provided around the pixel portion are integrally formed is manufactured. Is possible.

  However, the crystalline semiconductor film manufactured by the laser annealing method is formed by aggregating a plurality of crystal grains, and the positions and sizes of the crystal grains are random. A TFT manufactured over a glass substrate is formed by separating the crystalline semiconductor film into an island pattern for element isolation. However, in this case, it was not possible to form the crystal grains by specifying the position and size. Compared with the inside of a crystal grain, there are innumerable recombination centers and capture centers due to an amorphous structure, crystal defects, and the like at an interface (crystal grain boundary) of crystal grains. It is known that when carriers are trapped in this trapping center, the grain boundary potential rises and becomes a barrier against the carriers, so that the current transport characteristics of the carriers are reduced. The crystallinity of the semiconductor film in the channel formation region has a significant effect on the electrical characteristics of the TFT, but it is almost impossible to form the channel formation region with a single crystal semiconductor film by eliminating the influence of crystal grain boundaries. It was possible.

  In order to solve such a problem, various attempts have been made to form crystal grains having a large grain size which are controlled in position in the laser annealing method. The solidification process of the semiconductor film after irradiating the semiconductor film with a laser beam will be described below.

  It takes a certain amount of time for crystal nuclei to form in a semiconductor film completely melted by laser beam irradiation, and an infinite number of crystal nuclei are generated uniformly (or non-uniformly) in the completely melted region. The solidification process of the completely melted semiconductor film ends. In this case, the position and size of the crystal grains obtained are random.

  In addition, when the semiconductor film is not completely melted by the laser beam irradiation and the solid phase semiconductor region partially remains, crystal growth starts immediately from the solid phase semiconductor region after the laser beam irradiation. . As already mentioned, it takes some time for crystal nuclei to form in the complete melting region. Therefore, a solid-liquid interface (solid phase) that is the tip of crystal growth in a direction parallel to the film surface of the semiconductor film (hereinafter referred to as “lateral direction”) until crystal nuclei are generated in the complete melting region. By moving the semiconductor region and the complete melting region, the crystal grains grow to a length of several tens of times the film thickness. Such growth is terminated when a number of crystal nuclei are generated uniformly (or non-uniformly) in the complete melting region and the crystal grows. Hereinafter, this phenomenon is referred to as super lateral growth.

  Even in an amorphous semiconductor film or a polycrystalline semiconductor film, there is an energy region of a laser beam that realizes the super lateral growth. However, the energy range is very narrow, and the position where large crystal grains are obtained cannot be controlled. Further, the region other than the large crystal grains was a microcrystalline region or an amorphous region in which an infinite number of crystal nuclei were generated.

  As explained above, if the lateral temperature gradient can be controlled in the energy region of the laser beam in which the semiconductor film is completely melted (a heat flow in the lateral direction is generated), the growth position and growth direction of the crystal grains Can be controlled. Various attempts have been made to realize this method.

  First, a metal film (Cr single layer or a laminate in which an Al film is formed on a Cr film) is formed as a reflective film on the amorphous semiconductor film, and is partially etched to form a metal film on the amorphous semiconductor film. A region with and without a metal film is formed. Since the reflectance of Cr at a wavelength of 308 nm is about 60% and the reflectance of Al is about 90%, when a laser beam with a wavelength of 308 nm is irradiated, the amorphous semiconductor region below the metal film is a metal film. The laser beam is not irradiated as compared with the amorphous semiconductor region that is not covered. That is, a temperature gradient is generated between the amorphous semiconductor region below the metal film and the amorphous semiconductor region not covered with the metal film. Therefore, crystal nuclei generated in the amorphous semiconductor region below the metal film are laterally grown to an amorphous semiconductor region not covered with the molten metal film to form crystal grains of 1 to 2 μm. It is known that

  However, this method has the following problems. In the method of forming a metal film partially on an amorphous semiconductor film and performing crystallization by irradiating a laser beam, the position where the crystal grains are formed can be controlled, but the position where the single crystal unit is formed It was difficult to control. In addition, since the metal film is formed directly on the amorphous semiconductor film, the metal element diffuses into the amorphous semiconductor film, and the crystalline semiconductor produced by crystallizing the amorphous semiconductor film is used. When a TFT is manufactured, there is a possibility that the electrical characteristics of the TFT are deteriorated. In addition, cracks and peeling may occur in the metal film and the amorphous semiconductor film. The metal film is usually formed by sputtering. The sputtering method has a larger variation in the film thickness in the plane when the film is formed than the CVD method. For this reason, when the substrate is enlarged, it can be said that it is not preferable in the future to use the sputtering method.

Also, James S. of Columbia University. Im et al. Showed a sequential lateral solidification method (hereinafter referred to as “SLS method”) that can realize super lateral growth at an arbitrary place (see, for example, Patent Document 1).
Japanese Patent No. 3204986

In the SLS method, crystallization is performed by moving a slit-shaped mask about a distance (about 0.75 μm) at which super lateral growth is performed for each shot.

  When the SLS method is used, it is possible to perform lateral growth by irradiating an amorphous silicon film formed on a glass substrate with an ultrafine beam of about several microns focused on an excimer laser beam transmitted through a slit. . Further, by making the substrate feed pitch for each shot the lateral growth distance, the lateral growth can be sequentially connected. However, the use of the SLS method has the following problems.

  Since the excimer laser has poor beam quality, in order to use the SLS method, it is necessary to use a mask for condensing light of several μm in the laser irradiation apparatus. In addition, the mask needs to be replaced periodically, and lenses with short focal lengths have a shallow depth of focus. Therefore, in order to maintain a uniform focus within the substrate surface, auto-focusing is required to keep the depth of focus constant. The focus function becomes indispensable, and the apparatus becomes complicated and expensive as compared with a normal laser irradiation apparatus.

  In view of the above problems, an object of the present invention is to control the crystal lateral growth position of a semiconductor film without complicating the apparatus.

  Another object of the present invention is to control a crystal lateral growth position of a semiconductor film by using a laser annealing apparatus using a linear beam as it is.

  Further, the present invention realizes a TFT capable of high-speed operation by producing a crystalline semiconductor film in which the position and size of crystal grains are controlled and using the crystalline semiconductor film in a TFT channel formation region. The task is to do. It is another object of the present invention to provide a technology that can apply such TFTs to various semiconductor devices such as a liquid crystal display device and a display device using an electroluminescent material.

  In the present invention, in order to control the position of the crystal lateral growth of the semiconductor film, the patterned reflection film is formed on the semiconductor film. Then, the exposed semiconductor film is crystallized by irradiating the semiconductor film exposed by patterning the reflective film with a laser.

The structure of the invention related to the method for manufacturing a semiconductor device disclosed in this specification is as follows.
Forming a semiconductor film on an insulating substrate;
Forming a reflective film made of an insulating film on a part of the semiconductor film;
The exposed semiconductor film is crystallized by irradiating laser light with the reflective film as a mask.

Another structure of the invention relating to the method for manufacturing a semiconductor device disclosed in this specification is as follows:
Forming a semiconductor film on an insulating substrate;
Forming a reflective film made of an insulating film on the semiconductor film;
Patterning the reflective film to expose a portion of the semiconductor film;
The exposed semiconductor film is crystallized by irradiating a laser beam using the patterned reflective film as a mask.

Another structure of the invention relating to the method for manufacturing a semiconductor device disclosed in this specification is as follows:
Forming a base film on an insulating substrate;
Forming a semiconductor film on the base film;
Forming a reflective film made of an insulating film on the semiconductor film;
Patterning the reflective film to expose a portion of the semiconductor film;
By irradiating a laser beam using the patterned reflective film as a mask, the exposed semiconductor film is crystallized,
Removing the patterned reflective film;
Patterning a portion of the semiconductor film;
Forming a gate insulating film on the patterned semiconductor film;
Forming a gate electrode on the gate insulating film;
The crystallized semiconductor film is used for a channel formation region of a thin film transistor.

Another structure of the invention relating to the method for manufacturing a semiconductor device disclosed in this specification is as follows:
Forming a base film on an insulating substrate;
Forming a semiconductor film on the base film;
Irradiating the semiconductor film with a first laser beam;
Forming a reflective film made of an insulating film on the semiconductor film irradiated with the first laser beam;
Patterning the reflective film to expose a portion of the semiconductor film;
The exposed semiconductor film is crystallized by irradiating a second laser beam using the patterned reflective film as a mask.

Another structure of the invention relating to the method for manufacturing a semiconductor device disclosed in this specification is as follows:
Forming a base film on an insulating substrate;
Forming a semiconductor film on the base film;
Irradiating the semiconductor film with a first laser beam to form a crystalline semiconductor film;
Forming a reflective film made of an insulating film on the crystalline semiconductor film;
Patterning the reflective film to expose a portion of the crystalline semiconductor film;
Irradiation with a second laser beam using the patterned reflective film as a mask improves the crystallinity of the exposed semiconductor film while maintaining the orientation of the crystalline semiconductor film. .

  In the above structure of the invention, the semiconductor film provided under the reflective film is not melted by the irradiation with the second laser light.

  In the configuration of the invention described above, the reflective film reflects the second laser light.

  In the structure of the invention described above, the reflective film has a structure in which insulating films having a high refractive index and insulating films having a low refractive index are alternately stacked. Specifically, it is characterized by comprising a silicon oxide film and a silicon nitride film formed on and in contact with the silicon oxide film. More preferably, a reflective film is formed by stacking several layers of a silicon oxide film and a silicon nitride film.

  In the structure of the invention described above, the reflective film is formed by a CVD method typified by a plasma CVD method or a low pressure CVD method.

  In the configuration of the invention described above, the reflective film is patterned by dry etching.

  In the structure of the invention, the patterned reflective film is removed by wet etching.

  In the configuration of the invention described above, the crystallization is caused by lateral crystal growth, and the semiconductor film is exposed from a region of the semiconductor film provided under the patterned reflective film. Crystal growth is laterally (lateral) toward the region of the semiconductor film.

  In the structure of the above invention, the thin film transistor is formed so that the carrier moving direction in the channel formation region of the thin film transistor is parallel to the lateral crystal growth direction.

  In the structure of the invention described above, the semiconductor device is any one of a liquid crystal display device, an EL display device, and an integrated circuit.

  In the structure of the above invention, the semiconductor device is used for any one of a video camera, a digital camera, a navigation system, an audio playback device, a computer, a game machine, a portable information terminal, and an image playback device.

  In the present invention, in order to control the crystal lateral growth position of the semiconductor film, the patterned reflection film is formed on the semiconductor film. Then, the exposed semiconductor film is crystallized by irradiating the semiconductor film exposed by patterning the reflective film with a laser. Therefore, a mask for condensing to several μm is not used in the laser irradiation apparatus, and the conventionally used excimer laser can be used as it is, and an epitaxially grown crystal and a laterally grown crystal are separately formed within the substrate surface. Is also possible.

  In addition, since it is not necessary to purchase a new device, the cost can be reduced.

  Moreover, the following effects can be acquired by making a reflection film into the structure which laminates | stacks alternately an insulating film with a high refractive index, and an insulating film with a low refractive index. That is, as the number of laminated patterns of the insulating film having a high refractive index and the insulating film having a low refractive index is increased, the reflectance can be increased, and a structure for obtaining a desired reflectance can be easily formed. In addition, since the thickness of the reflection film formed as a whole can be reduced compared to the case where the reflection film is a single layer film, the reflection film is removed after patterning or crystallization of the reflection film. The etching time can be shortened. This is because when the reflective film is formed of a single layer film, if the film thickness is reduced, the film functions as a film having a low reflectance, that is, an antireflection film.

  Moreover, compared with the case where a semiconductor film is crystallized using an antireflection film, the present invention has the following advantageous effects. When the semiconductor film is crystallized using the antireflection film, the reflectance varies in the plane of the antireflection film according to the variation in the film thickness of the antireflection film. When the reflectance varies within the surface of the antireflection film, the energy absorbed by the semiconductor film varies. As a result, the crystallinity of the crystallized semiconductor film varies. On the other hand, a crystalline semiconductor film manufactured using the present invention is formed by directly irradiating a region where a semiconductor film is exposed without passing through another film. When the region where the semiconductor film is exposed is directly irradiated with laser, the energy absorbed in the region where the semiconductor film is exposed becomes constant in the plane of the region where the semiconductor film is exposed. As a result, the crystallinity of the crystallized semiconductor film is less likely to vary. Therefore, by using the crystalline semiconductor film manufactured according to the present invention for the channel formation region of the TFT, variations in characteristics of individual TFTs can be eliminated.

  Further, there is no contamination of the semiconductor film as compared with the case where a metal film is used for the reflective film. Further, when a metal film is formed by a CVD method, the metal film is formed by a sputtering method because a toxic gas must be used as a film forming gas. However, as the substrate becomes larger in the sputtering method, the film thickness in the surface during film formation tends to vary as compared with the CVD method, and cracks and peeling are likely to occur when the reflective film is removed.

  Since the reflective film used in the present invention is not subject to any restrictions on the formation by the CVD method, there is no need to worry about cracks or peeling when the reflective film is removed.

  In addition, by forming a TFT using the crystalline semiconductor film obtained by the present invention, electric characteristics such as field effect mobility (coefficient of carrier moving velocity with respect to electric field) and subthreshold coefficient (S value) are excellent. A TFT is obtained. Further, the use of this TFT is most suitable for manufacturing an integrated circuit that requires high characteristics such as response speed.

  The best mode for carrying out the present invention will be described with reference to FIG. In addition, when referring to the same target object in the structure of this invention demonstrated below, it demonstrates using the same code | symbol in different drawing.

  1A to 1D are cross-sectional views illustrating steps of manufacturing a semiconductor device by implementing the present invention.

  First, as illustrated in FIG. 1A, a base film 102 is formed over an insulating substrate 101 such as a glass substrate or a quartz substrate. As a method for forming the base film 102, a known method such as a CVD method typified by a plasma CVD method or a low pressure CVD method, or a sputtering method may be used.

  Next, the semiconductor film 103 is formed over the base film 102. As the semiconductor film 103, an amorphous semiconductor film such as an amorphous silicon film may be formed, but a microcrystalline semiconductor film or a crystalline semiconductor film may be formed.

Next, as illustrated in FIG. 1B, the reflective film 104 is formed over the semiconductor film 103. The reflective film 104 may have a structure in which insulating films having a high refractive index and insulating films having a low refractive index are alternately stacked. For example, as shown in FIG. 16A, a silicon oxynitride film 1651 (SiO _x N _y film) (x> y) (x and y are positive integers), a silicon nitride oxide film 1652 (SiN) in order from the substrate side. _x O _y film) (x> y) (x and y are positive integers) are stacked, or as shown in FIG. 16B, the first silicon oxynitride film 1653, A structure 1656 in which one silicon nitride oxide film 1654, a second silicon oxynitride film 1655, and a second silicon nitride oxide film are stacked may be used. What is important in the manufacturing process of the present invention is to form a reflective film without using a metal film as described above.

  Next, as shown in FIG. 1C, the reflective film 104 is patterned so that a part of the semiconductor film 103 is exposed. Note that in the semiconductor film 103, a region (first region) covered with the reflective film 104 is denoted by 110, and an exposed region (second region) is denoted by 111. As a patterning method, a known patterning technique may be used, but more preferably, patterning is performed by dry etching. This is because anisotropic etching can be performed by using dry etching, so that patterning can be performed with good control.

  Next, as shown in FIG. 1D, laser light is irradiated using the patterned reflective film as a mask. A process until the semiconductor film is crystallized by irradiation with laser light will be described.

  When the semiconductor film 103 is irradiated with laser light, the region 111 where the reflective film 104 is patterned and the semiconductor film 103 is exposed becomes a completely melted region.

  On the other hand, the laser beam is reflected in the region 110 covered with the reflective film. As a result, the threshold energy necessary for crystallization of the semiconductor film is not exceeded. That is, the region 110 covered with the reflective film does not melt and can be said to be a solid phase semiconductor region. In FIG. 1D, the laser light is described as being reflected only on the outermost surface of the reflective film 104, but in actuality, the laser light is also incident on the reflective film, and the reflected light is reflected. The light is reflected at the boundary surface of each insulating film constituting the film. Further, although the ratio of reflection is small, the laser light is also reflected between the interface between the lowermost layer of the laminated insulating film constituting the reflection film and the semiconductor film. The thickness of each laminated insulating film constituting the reflective film is designed so that the phases of reflected light returning to the incident side (more preferably, all reflected light returning to the incident side) are aligned. Preferably, the reflected light intensity increases due to the interference effect.

  A temperature gradient is generated between the completely molten region and the solid phase semiconductor region. It takes some time for crystal nuclei to form in the complete melting region. Therefore, the solid-liquid interface (the boundary between the solid-phase semiconductor region and the complete melting region) is the tip of crystal growth in the lateral direction with respect to the film surface of the semiconductor film until the crystal nucleus is generated in the complete melting region. ) Moves, crystal grains grow. In this growth, crystal grains grown at the center of the region 111 where the semiconductor film is exposed (dotted line portion shown in the crystalline semiconductor film 105 in FIG. 1D) are in contact with each other. finish. At the same time, a ridge is formed on the surface near the center of the region where the semiconductor film is exposed. In this manner, the region 111 where the semiconductor film 103 is exposed is crystallized, and the crystalline semiconductor film 105 in which the growth position and growth direction of crystal grains are controlled is formed. Note that “ridge” in this specification refers to a protrusion formed on the surface of a semiconductor film when crystal grains grown by laser light irradiation come into contact with each other.

The laser beam used in this step is a pulse oscillation type laser beam, and any type of laser beam can be used as long as it is capable of pulse oscillation. For example, Ar laser, Kr laser, excimer laser, CO ₂ laser, YAG laser, Y ₂ O ₃ laser, YVO ₄ laser, GdVO ₄ laser, YLF laser, YAlO ₃ laser, glass laser, ruby laser, alexandrite laser, Ti: Any one of sapphire laser, copper vapor laser or gold vapor laser can be used.

The energy density of the irradiated laser beam varies depending on the thickness of the semiconductor film, the pulse width of the irradiated laser beam, the wavelength, and the like. For example, if a semiconductor film having a thickness of 50 nm is crystallized using a XeCl excimer laser, it may be performed at 400 to 1000 mJ / cm ² .

  Further, the shape of the laser beam to be irradiated may be processed into a linear shape or may be processed into a planar shape.

  In the present invention, as shown in FIG. 1 (C), the width between the reflective films adjacent to each other (the width of the slit) is set to 1 to 10 μm (preferably 2 to 3 μm). The entire region where the semiconductor film is exposed by patterning can be laterally grown. That is, if the width of the slit is 10 μm or more, a region (seed crystal) that solidifies before the region that is completely melted by laser irradiation and laterally grows is generated. It becomes impossible.

  Next, all the patterned reflective film is removed. As a method of removing the patterned reflective film, a known etching technique may be used, but it is more preferable to remove the patterned reflective film by wet etching. This is because, when wet etching is used, the etching selectivity between the semiconductor film and the silicon oxide film used as the reflective film can be increased as compared with dry etching. That is, by using wet etching, the reflective film can be removed without overetching the crystallized semiconductor film.

  Through the above steps, the crystalline semiconductor film 105 in which the crystal grain growth position and growth direction are controlled can be obtained.

  In this embodiment, a process for manufacturing a crystalline semiconductor film and manufacturing a TFT using the obtained crystalline semiconductor film will be described with reference to FIGS.

First, as illustrated in FIG. 1A, a base film 102 is formed over an insulating substrate 101 such as a glass substrate or a quartz substrate. As a method for forming the base film 102, a known method such as a CVD method typified by a plasma CVD method or a low pressure CVD method, or a sputtering method may be used. As the base film 102, a silicon oxide film (SiO _x film), a silicon nitride film (SiN _x film), a silicon oxynitride film (SiO _x N _y film) (x> y) (x and y are positive integers) ), A silicon nitride oxide film (SiN _x O _y film) (x> y) (x and y are positive integers), or a structure in which these are appropriately stacked. . In this embodiment, the base film 102 is formed by stacking a silicon nitride oxide film by 50 nm and a silicon oxynitride film by 100 nm.

  Next, the semiconductor film 103 is formed over the base film 102. An amorphous semiconductor film may be formed as the semiconductor film 103, but a microcrystalline semiconductor film or a crystalline semiconductor film may be formed. There is no limitation on the material of the semiconductor film, but silicon or silicon germanium (SiGe) is preferably used. In this embodiment, an amorphous silicon film is formed to 54 nm. Note that a step of removing hydrogen contained in the semiconductor film may be performed after the semiconductor film is formed. Specifically, heating may be performed at 500 ° C. for 1 hour.

  In addition, when the base film 102 and the semiconductor film 103 are formed, if the interface between the base film 102 and the semiconductor film 103 is not exposed to the atmosphere, contamination of the interface can be prevented, and characteristics of the manufactured TFT can be prevented. Can be reduced. In this embodiment, the base film 102 and the semiconductor film 103 are continuously formed using the plasma CVD method without being exposed to the atmosphere.

  Next, as illustrated in FIG. 1B, the reflective film 104 is formed over the semiconductor film 103. The reflective film 104 may have a structure in which insulating films are stacked.

  Here, the reflectance of the reflective film at 308 nm which is the wavelength of the excimer laser (XeCl) is shown in FIG. FIG. 3 shows the result of simulating the reflectivity when the thickness of each film is changed as a two-layer structure in which a silicon oxide film and a silicon nitride film are stacked on the silicon oxide film as the reflection film. FIG. 3 shows that the reflectance when the reflective film is not provided (that is, when the thicknesses of the silicon oxide film and the silicon nitride film are each 0 nm) is about 55%. It can also be seen that when the reflective film is formed by laminating a silicon oxide film of 45 nm and a silicon nitride film of 40 nm, the reflectance is about 68%. Therefore, when crystallization is performed by irradiating excimer laser (XeCl), the reflective film preferably has a reflectance of 65% or more.

  In FIG. 3, the reflective film has a structure in which two layers of a silicon oxide film and a silicon nitride film are stacked. However, by further stacking four layers and six layers, the reflectance of the reflective film can be further improved. I can expect. In this embodiment, the silicon oxide film is laminated to 45 nm and the silicon nitride film is laminated to 40 nm.

  Next, as shown in FIG. 1C, the reflective film 104 is patterned so that a part of the semiconductor film is exposed. As a patterning method, a known patterning technique may be used, but more preferably, patterning is performed by dry etching. When dry etching is used, anisotropic etching is possible, so that patterning can be performed with good control. Note that in the semiconductor film 103, a region (first region) covered with the reflective film 104 is denoted by 110, and an exposed region (second region) is denoted by 111.

  The width between the reflective films (the width of the slits) may be 1 to 10 μm, and preferably 2 to 3 μm.

  Next, as shown in FIG. 1D, the region 111 where the semiconductor film 103 is exposed is crystallized by irradiating laser light using the patterned reflective film as a mask, so that a crystalline semiconductor film 105 is formed. At this time, the crystallinity of the region 110 where the semiconductor film 103 is covered with the reflective film may be improved depending on the conditions of the reflective film and the laser beam, but the crystallinity is inferior to the crystalline semiconductor film 105. It is. Prior to this step, an element that promotes crystallization of a semiconductor film such as Ni was added using the patterned reflective film as a mask, followed by solid phase growth, and then the semiconductor film was exposed by laser irradiation. The crystalline semiconductor film 105 may be formed by crystallizing the region. As an element that promotes crystallization, one or more kinds of elements selected from Fe, Co, Ni, Ru, Rh, Pd, Os, Ir, Pt, Cu, and Au can be used.

The laser beam used in this embodiment is a pulse oscillation type laser beam, and any type of laser beam can be used as long as it is capable of pulse oscillation. For example, Ar laser, Kr laser, excimer laser, CO ₂ laser, YAG laser, Y ₂ O ₃ laser, YVO ₄ laser, GdVO ₄ laser, YLF laser, YAlO ₃ laser, glass laser, ruby laser, alexandrite laser, Ti: Any one of sapphire laser, copper vapor laser or gold vapor laser can be used. In this embodiment, an excimer laser (XeCl) is used.

The energy density of the irradiated laser beam varies depending on the thickness of the semiconductor film, the pulse width of the irradiated laser beam, the wavelength, and the like. For example, if a semiconductor film having a thickness of 50 nm is crystallized using a XeCl excimer laser, it may be performed at 400 to 1000 mJ / cm ² .

Next, all of the patterned reflective film is removed so that the entire surface of the semiconductor film is exposed. As a method of removing the patterned reflective film, a known etching technique may be used, but it is more preferable to remove the patterned reflective film by wet etching. This is because using wet etching can increase the etching selectivity between the semiconductor film and the silicon oxide film used as the reflective film, compared to dry etching. That is, the reflective film can be removed without overetching the crystallized semiconductor film. In this example, a mixed solution containing 7.13 wt% ammonium hydrogen fluoride (NH ₄ HF ₂ ) and 15.4 wt% ammonium fluoride (NH ₄ F) (trade name: LAL500, manufactured by Stella Chemifa Corporation) was used. The reflective film is used as an etchant and wet-etched at room temperature.

  Next, after exposing the entire surface of the semiconductor film, an impurity imparting p-type conductivity such as boron is doped on the entire surface of the exposed semiconductor film. By this step, channel doping is performed in a region that becomes a channel formation region of the TFT, and the threshold value of the TFT can be controlled.

  Next, as illustrated in FIG. 2A, the semiconductor film 110 is patterned to form an island-shaped semiconductor film. A known patterning technique may be used as a patterning method. Further, the semiconductor film 110 may be entirely patterned or a part thereof may be patterned. In this embodiment, the crystalline semiconductor film 105 is not patterned, and only a part of the semiconductor film 110 is patterned.

  Next, after the semiconductor film 110 is patterned as shown in FIG. 2B, an insulating film (gate insulating film) 106 is formed. The insulating film 106 may have a single-layer structure using any one of a silicon oxide film, a silicon nitride film, a silicon oxynitride film, and a silicon nitride oxide film, or a structure in which these layers are stacked as appropriate.

  Next, as shown in FIG. 2C, after the insulating film 106 is formed, a metal film is formed, and a part of the metal film is patterned to form the gate electrode 107. As the metal film, Al, Mo, W, or the like can be used, and a single layer structure or a laminated structure of these metals may be used. For example, a stacked structure in which W is formed on TaN can be used. Further, the gate electrode 107 may be formed using a polysilicon film instead of the metal film.

FIG. 4A shows a cross-sectional view at the stage where the gate electrode 107 is formed, and FIG. 4B shows a top view thereof. The cross-sectional view in FIG. 4A corresponds to a cross-sectional view along AA ′ in the top view in FIG. In forming the gate electrode 107, it is preferable that a region where a ridge exists in the island-shaped semiconductor film is not included under the region where the gate electrode 107 is formed. In other words, the channel formation region of the TFT formed under the gate electrode 107 is preferably formed using the crystalline semiconductor film 105 having almost no ridge among the island-shaped semiconductor films. However, as described above, the crystalline semiconductor film 105
Since it includes a region where a ridge exists (in FIG. 1D, a dotted line portion shown in the crystalline semiconductor film 105), it is preferable not to include this region. In FIG. 4, a part of the semiconductor film 110 is etched to form an island-shaped semiconductor film, and a TFT channel formation region is formed using the crystalline semiconductor film 105 having almost no ridge among the island-shaped semiconductor films. Is preferable.

  Further, as shown in FIG. 5, patterning is performed so as to leave a part of the crystalline semiconductor film 105 to form an island-shaped semiconductor film, and a gate electrode is formed on the crystalline semiconductor film 105 having almost no ridge. May be. FIG. 5A is a cross-sectional view at the stage where the gate electrode 107 is formed, and FIG. 5B is a top view thereof. The cross-sectional view in FIG. 5A corresponds to a cross-sectional view between BB ′ in the top view in FIG. Eventually, patterning may be performed other than those shown in FIGS. 4 and 5 as long as the gate electrode 107 can be formed on the crystalline semiconductor film 105 having almost no ridge.

  Next, an impurity imparting n-type conductivity such as phosphorus is doped using the gate electrode 107 as a mask. By this step, the source and drain regions of the TFT are formed in a self-aligned manner.

  Next, as illustrated in FIG. 2D, an interlayer insulating film 108 is formed over the insulating film 106 and the gate electrode 107. The interlayer insulating film 108 may have a single layer structure or a multilayer structure. Further, as the material of the interlayer insulating film 108, a material having self-flatness (for example, a coating film of acrylic, polyimide, siloxane, or the like) can be used. In addition, a silicon oxide film, a silicon nitride film, a silicon oxynitride film, a silicon nitride oxide film, or the like can be combined as appropriate. In this embodiment, an insulating film made of an organic resin is stacked on the inorganic insulating film. Siloxane has a skeletal structure composed of a bond of silicon (Si) and oxygen (O), and an organic group containing at least hydrogen (for example, an alkyl group or aromatic hydrocarbon) or a fluoro group is used as a substituent. That's fine. Further, as a substituent, an organic group containing at least hydrogen and a fluoro group may be used together.

  Next, as shown in FIG. 2E, contact holes are formed in the interlayer insulating film 108 so as to reach the source and drain regions of the TFT. The shape of the contact hole is preferably a tapered shape.

  Next, a wiring (electrode) 109 is formed over the contact hole. As the wiring 109, Al, Cu, Ag, Ti, Mo, or the like can be used, and a single-layer structure or a laminated structure of these metals may be used. For example, a structure in which Ti, Al, and Ti are sequentially stacked, or a structure in which Mo, Al, and Mo are sequentially stacked can be employed. In addition, an alloy containing Al and C can also be used. This alloy may contain Ni, Co, Fe, Si, or the like. These contents are, for example, 0.1 to 3.0 atomic% for C, 0.5 to 7.0 atomic% for at least one element among Ni, Co, and Fe, and 0.5 to 2 for Si. It is preferable to set it to 0 atomic%.

  Through the above steps, a TFT using the crystalline semiconductor film manufactured according to the present invention for the channel formation region of the TFT can be manufactured.

  The crystalline semiconductor film 105 manufactured in this embodiment is formed by directly irradiating the region 111 where the semiconductor film 103 is exposed without passing through another film. When the semiconductor film 103 is irradiated with laser light through another film, the energy absorbed in the semiconductor film 103 varies depending on the film thickness variation of the film. As shown in this embodiment, when the region 111 where the semiconductor film 103 is exposed is directly irradiated with laser, the energy absorbed in the region 111 where the semiconductor film 103 is exposed is the energy of the region 111 where the semiconductor film 103 is exposed. It is constant in the plane. Therefore, when a plurality of TFTs are manufactured by forming a channel formation region of TFTs using the crystalline semiconductor film 105, variation in characteristics among individual TFTs can be eliminated.

  Note that although a process for manufacturing an n-channel TFT is described in this embodiment, a p-channel TFT can also be manufactured by using the present invention.

  In this embodiment, a method for manufacturing a crystalline semiconductor film by using a method different from that in Embodiment 1 will be described with reference to FIGS.

  First, as illustrated in FIG. 6A, a base film 102 is formed over an insulating substrate 101 such as a glass substrate or a quartz substrate. As a method for forming the base film 102, a known method such as a CVD method typified by a plasma CVD method or a low pressure CVD method, or a sputtering method may be used. The base film 102 may have a single-layer structure using any one of a silicon oxide film, a silicon nitride film, a silicon oxynitride film, and a silicon nitride oxide film, or may have a structure in which these layers are stacked as appropriate. In this embodiment, as the base film 102, a silicon nitride oxide film and a silicon oxynitride film are stacked.

  Next, an amorphous semiconductor film 301 is formed over the base film 102.

  Next, the amorphous semiconductor film 301 is crystallized to form a crystalline semiconductor film 302.

  As a crystallization method, a known method of crystallization using heating or Ni may be used, but crystallization by laser irradiation is preferable, and in this embodiment, an example of crystallization by laser irradiation is shown.

  The laser used for crystallization may be a pulse oscillation type laser or a continuous oscillation type laser.

Laser light capable of pulse oscillation includes Ar laser, Kr laser, excimer laser, CO ₂ laser, YAG laser, Y ₂ O ₃ laser, YVO ₄ laser, GdVO ₄ laser, YLF laser, YAlO ₃ laser, glass laser, A ruby laser, an alexandrite laser, a Ti: sapphire laser, a copper vapor laser, a gold vapor laser, or the like can be used.

The energy density of the irradiated laser beam varies depending on the thickness of the semiconductor film, the pulse width of the irradiated laser beam, the wavelength, and the like. For example, if a semiconductor film having a thickness of 50 nm is crystallized using a XeCl excimer laser, it may be performed at 400 to 1000 mJ / cm ² .

As a laser beam capable of continuous oscillation, a gas laser or a solid laser can be used. Examples of the gas laser include an Ar laser and a Kr laser. As the solid laser, crystals such as YAG, YVO ₄ , YLF, YAlO ₃ , Y ₂ O ₃ , GdVO ₄ doped with Cr, Nd, Er, Ho, Ce, Co, Ti, Yb or Tm are used. A laser or the like can also be used. The fundamental wave of the solid-state laser varies depending on the material to be doped, and laser light having a fundamental wave of around 1 μm can be obtained. The harmonic with respect to the fundamental wave can be obtained by using a nonlinear optical element. Typically, the second harmonic (532 nm) and the third harmonic (355 nm) of an Nd: YVO ₄ laser (fundamental wave 1064 nm) can be mentioned. Specifically, laser light emitted from a continuous wave YVO ₄ laser is converted into a harmonic by a non-linear optical element to obtain laser light with an output of 10 W. There is also a method of emitting harmonics by putting a YVO ₄ crystal and a nonlinear optical element in a resonator. Preferably, the laser beam is shaped into a rectangular or elliptical shape on the irradiation surface by an optical system, and the object to be processed is irradiated. In this case, a power density of about 0.01 to 100 MW / cm ² (preferably 0.1 to 10 MW / cm ²⁾ is required. Then, the insulating substrate 101 is moved relative to the laser beam at a speed of about 10 to 2000 cm / sec.

  Next, as illustrated in FIG. 6B, the reflective film 104 is formed over the crystalline semiconductor film 302. The reflective film 104 may have a structure in which insulating films are stacked. For example, a silicon oxynitride film and a silicon nitride oxide film may be stacked.

  Next, as shown in FIG. 6C, the reflective film 104 is patterned so that part of the crystalline semiconductor film 302 is exposed. Of the crystalline semiconductor film 302, a region covered with the reflective film 104 is denoted by 310, and an exposed region is denoted by 311. As a patterning method, a known patterning technique may be used, but more preferably, patterning is performed by dry etching. When dry etching is used, anisotropic etching is possible, so that patterning can be performed with good control.

  Further, the width between the reflective films adjacent to each other (slit width) may be 1 to 10 μm, and preferably 2 to 3 μm.

  Next, as shown in FIG. 6D, laser light is irradiated again using the patterned reflective film as a mask to recrystallize the exposed region 311 of the crystalline semiconductor film 302. In this embodiment, the amorphous semiconductor film 301 is crystallized in advance, and then the crystallinity is further improved by irradiating laser in this step. This improvement in crystallinity is attributed to the fact that the amorphous semiconductor film 301 is laterally grown under the influence of the orientation of the crystallized semiconductor film 302. In FIG. 6D, for convenience, the laser light is reflected only on the outermost surface of the reflective film 104, but actually the laser light is also incident on the reflective film and is reflected. The light is reflected at the boundary surface of each insulating film constituting the film. Further, although the ratio of reflection is small, the laser light is also reflected between the interface between the lowermost layer of the laminated insulating film constituting the reflection film and the semiconductor film. The thickness of each laminated insulating film constituting the reflective film is designed so that the phases of reflected light returning to the incident side (more preferably, all reflected light returning to the incident side) are aligned. Preferably, the reflected light intensity increases due to the interference effect.

The laser beam used in this step is a pulse oscillation type laser beam, and any type of laser beam can be used as long as it is capable of pulse oscillation. For example, Ar laser, Kr laser, excimer laser, CO ₂ laser, YAG laser, Y ₂ O ₃ laser, YVO ₄ laser, GdVO ₄ laser, YLF laser, YAlO ₃ laser, glass laser, ruby laser, alexandrite laser, Ti: Any one of sapphire laser, copper vapor laser or gold vapor laser can be used.

The energy density of the irradiated laser beam varies depending on the thickness of the semiconductor film, the pulse width of the irradiated laser beam, the wavelength, and the like. For example, if a semiconductor film having a thickness of 50 nm is crystallized using a XeCl excimer laser, it may be performed at 400 to 1000 mJ / cm ² .

  Through the above steps, a crystalline semiconductor film can be manufactured. The steps up to manufacturing a TFT using a crystalline semiconductor film are omitted here because the method described in Embodiment 1 can be applied.

  In this embodiment, an example in which the crystalline semiconductor film manufactured using the method described in Embodiment 1 or 2 is applied to a display device typified by a liquid crystal display device or an EL display device will be described.

  As shown in FIG. 7A, after patterning a crystalline semiconductor film 704 formed by crystallizing a semiconductor film over a substrate 701 using the method described in Embodiment 1 or 2, the gate insulating film 705 is formed. The gate insulating film 705 may have a single-layer structure using any one of a silicon oxide film, a silicon nitride film, a silicon oxynitride film, and a silicon nitride oxide film, or a structure in which these layers are stacked as appropriate. In this embodiment, the gate insulating film is formed by sequentially stacking a silicon oxynitride film and a silicon nitride oxide film. Note that steps up to the formation of the crystalline semiconductor film 704 may be performed using the method described in Embodiment 1 or Embodiment 2, and thus description thereof is omitted here.

  Next, as illustrated in FIG. 7B, a gate electrode 706 is formed over the gate insulating film 705. As a material of the conductive film used for the gate electrode 706, Al, Mo, W, or the like can be used, and a single layer structure or a stacked structure of these metals may be used. Further, a polysilicon film may be used as the conductive film. In this embodiment, tantalum nitride (TaN) is stacked to 30 nm and tungsten (W) is stacked to 370 nm. At this time, it is more preferable that the width of TaN is 0.5 to 1.5 μm wider than W.

  Next, using the gate electrode 706 as a mask, the crystalline semiconductor film 704 is doped with an impurity imparting p-type conductivity such as boron (B). By this step, the source region and drain region of the TFT can be formed in a self-aligned manner. In this embodiment, a low concentration impurity region (LDD region) is formed between a channel formation region of TFT and a source region and a drain region by a known doping method, but no low concentration impurity region is provided. It is good also as a structure.

  In addition, after the doping, heat treatment, intense light irradiation, or laser light irradiation may be performed in order to activate the impurity element doped in the impurity region. Accordingly, not only activation of the impurity element but also plasma damage to the gate insulating film 705 and plasma damage to the interface between the gate insulating film 705 and the semiconductor layer can be recovered.

Next, as illustrated in FIG. 7C, a first interlayer insulating film 707 is formed over the gate insulating film 705 and the gate electrode 706. The first interlayer insulating film 707 includes a silicon oxide film (SiO _x film), a silicon nitride film (SiN _x film), a silicon oxynitride film (SiO _x N _y film) (x> y) (x and y are positive) An integer), a silicon nitride oxide film (SiN _x O _y film) (x> y) (x and y are positive integers), or a structure in which these are appropriately laminated. Good. In this embodiment, the silicon nitride oxide film is stacked to 100 nm and the silicon oxynitride film is stacked to 900 nm.

  After the first interlayer insulating film 707 is formed, heat treatment is performed at 300 to 550 ° C. (more preferably 400 to 500 ° C.) for 1 to 12 hours in a nitrogen atmosphere to form the crystalline semiconductor film 704 (semiconductor layer). It is preferable to perform a hydrogenation step. Through this step, dangling bonds in the semiconductor layer can be terminated by hydrogen contained in the first interlayer insulating film 707. In this embodiment, heat treatment is performed at 410 ° C. for 1 hour.

  Next, as shown in FIG. 7D, contact holes are formed in the first interlayer insulating film 707 so as to reach the source and drain regions of the TFT. The shape of the contact hole is preferably a tapered shape.

  Next, a wiring 708 (electrode) is formed so as to cover the contact hole. The wiring 708 functions as a source electrode or a drain electrode. As the wiring 708, a metal such as Ag, Au, Cu, Ni, Pt, Pd, Ir, Rh, W, Al, Ta, Mo, Cd, Zn, Fe, Ti, Si, Ge, Zr, Ba, or an alloy thereof. Or a metal nitride thereof. Moreover, it is good also as these laminated structure. In this embodiment, titanium (Ti) is formed to 100 nm, an alloy of aluminum and silicon (Al—Si) is formed to 700 nm, titanium (Ti) is formed to 200 nm, and patterned into a desired shape.

  Next, as illustrated in FIG. 7E, a second interlayer insulating film 709 is formed over the first interlayer insulating film 707 and the wiring 708. The second interlayer insulating film 709 may have a single layer structure or a multilayer structure. Further, as the material of the second interlayer insulating film 709, a material having self-flatness (eg, a coating film of acrylic, polyimide, siloxane, or the like) can be used. In this embodiment, the second interlayer insulating film 709 is formed by baking the siloxane coating film. In this embodiment, a single-layer structure of siloxane is described as the second interlayer insulating film 709; however, a stacked structure having siloxane as the uppermost layer may be used.

  Next, after a contact hole is formed in the second interlayer insulating film 709, a first electrode 710 for electrically connecting to the wiring 708 through the contact hole is formed. As the first electrode 710, indium tin oxide containing silicon oxide (also referred to as indium tin oxide containing silicon oxide; hereinafter referred to as “ITSO”), zinc oxide, tin oxide, indium oxide, or the like can be used. . Alternatively, a transparent conductive film such as an indium zinc oxide alloy formed using a target in which 2 to 20 wt% zinc oxide (ZnO) is mixed with indium oxide can be used. In addition to the transparent conductive film, a titanium nitride film or a titanium film may be used. In this case, after forming the transparent conductive film, the titanium nitride film or the titanium film is formed to a thickness that allows light to pass therethrough (preferably about 5 to 30 nm). In this embodiment, an ITSO film is formed to 110 nm as the electrode 710.

  Alternatively, the first electrode 710 may be cleaned by polishing with a CMP method or a polyvinyl alcohol-based porous body so that the surface thereof is planarized. Further, after the polishing using the CMP method, the surface of the first electrode 710 may be subjected to ultraviolet irradiation, oxygen plasma treatment, or the like.

  Further, heat treatment may be performed after the first electrode 710 is formed. By this heat treatment, the transmittance of the transparent conductive film can be increased; thus, a highly reliable display device can be manufactured. In this embodiment, heat treatment is performed at 250 ° C. for 1 hour.

  In this embodiment, the process for manufacturing a p-channel TFT has been described. However, the present invention can also be applied to manufacturing an n-channel TFT by doping an impurity imparting n-type conductivity into the crystalline semiconductor film 704 using the gate electrode as a mask. The present invention can also be applied to the case where a p-channel TFT and an n-channel TFT are formed over the same substrate.

  The TFT may have a single gate structure in which one channel formation region is formed, a double gate structure in which two channel formation regions are formed, or a triple gate structure in which three channel formation regions are formed. The thin film transistor in the peripheral driver circuit region may have a single gate structure, a double gate structure, or a triple gate structure.

  In addition to the TFT manufacturing method shown in this embodiment, the top gate type (planar type), the bottom gate type (inverse stagger type), or 2 disposed above and below the channel formation region via a gate insulating film. The present invention can also be applied to a structure having two gate electrodes.

  Through the above steps, a display device typified by a liquid crystal display device or an EL display device with high electrical characteristics can be manufactured using the crystalline semiconductor film manufactured according to the present invention.

  In this example, a process until the first electrode is formed without forming the second interlayer insulating film 709 in the display device manufactured in Example 3 will be described. Therefore, repetitive description of the same portion or a portion having a similar function is omitted.

  In this embodiment, the steps up to the step of forming the gate electrode 706 are the same as those described in Embodiment 3, and the subsequent steps will be described.

  First, as illustrated in FIG. 11, a first interlayer insulating film 1107 is formed over the gate insulating film 705 and the gate electrode 706. In this embodiment, a first interlayer insulating film 1107 is formed as a two-layer structure of a silicon nitride oxide film and siloxane. Note that a film formed of silicon oxide, silicon nitride, silicon oxynitride, aluminum oxide, aluminum nitride, aluminum oxynitride, or another inorganic insulating material may be used instead of the silicon nitride oxide film.

  Next, contact holes are formed in the first interlayer insulating film 1107 so as to reach the source region and the drain region of the TFT. The shape of the contact hole is preferably a tapered shape.

  Next, a wiring 1108 (electrode) is formed so as to cover the contact hole. The wiring 1108 functions as a source electrode or a drain electrode.

  Next, a wiring 1108 connected to the source region or drain region of the semiconductor layer of the TFT is formed, and then a first electrode 1110 is formed so as to overlap with part of the wiring 1108.

  The first electrode 1110 functions as a pixel electrode, and the same material as the first electrode 710 in Embodiment 3 may be used. Also in this embodiment, in order to extract light through the first electrode 1110 as in the third embodiment, ITSO which is a transparent conductive film is formed as the first electrode 1110.

  Next, an insulating film 1111 is formed so as to cover the end portion of the first electrode 1110 and the TFT. The insulating film 1111 may be formed using the same material as the insulating film 709 described in Embodiment 3, but in this embodiment, acrylic is used as the insulating film 1111.

  Next, an electroluminescent layer 1112 is formed over the first electrode 1110 and a second electrode 1113 is stacked to form a light-emitting element. A passivation film is formed so as to cover the second electrode 1113. Finally, the substrate 701 is bonded to the sealing substrate with a sealing material. Note that a region surrounded by the sealing material may be filled with a filler.

  In the display device in FIG. 12, the connection structure between the wiring 1208 and the first electrode 1210 has a structure in which the wiring 1208 overlaps part of the first electrode 1210. In order to obtain such a connection structure, after forming the first electrode 1210 on the first interlayer insulating film 1207, a contact hole is formed in the first interlayer insulating film 1207, and then on the first electrode 1210. The wiring 1208 may be formed so as to overlap with part of the wiring. With this structure, the first electrode 1210 can be formed over siloxane; thus, coverage is good. Further, polishing treatment such as CMP can be sufficiently performed on the first electrode 1210, and there is an advantage that the first electrode 1210 can be formed with high flatness.

  Through the above steps, a display device typified by a liquid crystal display device or an EL display device with high electrical characteristics can be manufactured using the crystalline semiconductor film manufactured according to the present invention.

  In this embodiment, a display device (an EL display) having an electroluminescence element (hereinafter referred to as an “EL element”) using the crystalline semiconductor film manufactured by the method described in Embodiment 1 or Embodiment 2. A method for manufacturing the device will be described.

  In this embodiment, the first electrode 810 is formed using a light-transmitting film so that light from the electroluminescent element is extracted from the first electrode 810 side. In this embodiment, as in Embodiment 3, indium tin oxide containing silicon oxide (ITSO) is used as the first electrode 810.

  First, as illustrated in FIG. 8, an insulating film 811 (referred to as a bank, a partition, a barrier, a bank, or the like) is formed so as to cover the end portion of the first electrode 810 and the TFT.

  As the insulating film 811, silicon oxide, silicon nitride, silicon oxynitride, aluminum oxide, aluminum nitride, aluminum oxynitride, other inorganic insulating materials, acrylic acid, methacrylic acid, and derivatives thereof, polyimide, aromatic, or aromatic A heat-resistant polymer such as an aromatic polyamide, polybenzimidazole, or siloxane can be used. In addition, you may form using photosensitive and non-photosensitive materials, such as an acryl and a polyimide. In this embodiment, the insulating film 811 is formed using photosensitive polyimide so as to have a thickness of 1.5 μm in a flat region.

  The insulating film 811 preferably has a shape in which the radius of curvature continuously changes, and the coverage of the electroluminescent layer 812 (a layer containing an organic compound) and the second electrode 813 formed over the insulating film 811 is improved. Can do.

  In order to further improve reliability, heat treatment is preferably performed before the electroluminescent layer 812 is formed. By the heat treatment, moisture contained in and attached to the first electrode 810 and the insulating film 811 is preferably released. In this embodiment, heat treatment is performed at 300 ° C. for 1 hour.

  Next, an electroluminescent layer 812 is formed over the first electrode 810. Although only one pixel is shown in FIG. 8, electroluminescent layers corresponding to each color of red (R), green (G), and blue (B) are separately formed in this embodiment. In this embodiment, materials that emit red (R), green (G), and blue (B) light are selectively formed as the electroluminescent layer 812 by an evaporation method using an evaporation mask. The materials that emit red (R), green (G), and blue (B) light can be selectively formed by a vapor deposition method using a vapor deposition mask or a droplet discharge method. In the case of the droplet discharge method, there is an advantage that RGB can be separately applied without using a mask. In this embodiment, materials that emit red (R), green (G), and blue (B) light are formed by an evaporation method.

Next, a second electrode 813 made of a conductive film is formed over the electroluminescent layer 812. As the second electrode 813, a material having a low work function (Al, Ag, Li, Ca, or an alloy thereof, MgAg, MgIn, AlLi, CaF ₂ , or CaN) may be used. Thus, a light-emitting element including the first electrode 810, the electroluminescent layer 812, and the second electrode 813 is formed.

  In the display device illustrated in FIG. 8, light emitted from the light-emitting element passes through a film formed between the substrate 801 and the first electrode 810 and is emitted from the first electrode 810 side in the direction of the arrow.

  In addition, it is effective to provide a passivation film so as to cover the second electrode 813. Examples of the passivation film include silicon nitride, silicon oxide, silicon oxynitride (SiON), silicon nitride oxide (SiNO), aluminum nitride (AlN), aluminum oxynitride (AlON), and oxynitride in which the nitrogen content is higher than the oxygen content The insulating film includes aluminum (AlNO) or aluminum oxide, diamond-like carbon (DLC), and a nitrogen-containing carbon film (CN), and a single layer or a combination of the insulating films can be used.

  At this time, it is preferable to use a film with good coverage as the passivation film, and it is effective to use a carbon film, particularly a DLC film. Since the DLC film can be formed in a temperature range from room temperature to 100 ° C., it can be easily formed over the electroluminescent layer 812 having low heat resistance. In addition, the DLC film has a high blocking effect against oxygen and can suppress oxidation of the electroluminescent layer 812. Therefore, the problem that the electroluminescent layer 812 is oxidized during the subsequent sealing step can be prevented.

  Next, the substrate 801 over which the light-emitting element is formed and the sealing substrate are fixed with a sealant, and the light-emitting element is sealed. Since intrusion of moisture from the cross section is blocked by the sealing material, deterioration of the light emitting element can be prevented and the reliability of the display device is improved. Note that a region surrounded by the sealing material may be filled with a filler, or nitrogen or the like may be sealed by sealing in a nitrogen atmosphere. Further, the filler can be dropped in a liquid state and filled in the display device. In this embodiment, since it is a bottom emission type, it is not necessary to use a filler having translucency. However, in the case of a structure for extracting light through the filler, use a material having translucency. It is necessary to form a filler. As an example of the filler, visible light curing, ultraviolet curing, or thermosetting epoxy resin can be given. Through the above steps, a display device having a light-emitting element is completed.

  Further, it is preferable to install a desiccant in the EL display panel in order to prevent deterioration of the element due to moisture. In this embodiment, a desiccant is placed in a recess formed in the sealing substrate so as to surround the pixel region, and the thickness is not hindered. In addition, by installing a desiccant in the region corresponding to the gate wiring layer, the water absorption area can be increased, and the water absorption effect is high. Further, since the desiccant is formed on the gate wiring layer that does not emit light directly, the light extraction efficiency is not lowered.

  Note that in this embodiment, the case where a light-emitting element is sealed with a glass substrate is described; however, the sealing process is a process for protecting the light-emitting element from moisture and is mechanically sealed with a cover material. Any of a method, a method of encapsulating with a thermosetting resin or an ultraviolet light curable resin, or a method of encapsulating with a thin film having a high barrier ability such as a metal oxide or a nitride is used. As the cover material, glass, ceramics, plastic, or metal can be used. However, when light is emitted to the cover material side, it must be translucent. In addition, the cover material and the substrate on which the light emitting element is formed are bonded together using a sealing material such as a thermosetting resin or an ultraviolet light curable resin, and the resin is cured by heat treatment or ultraviolet light irradiation treatment to form a sealed space. Form. It is also effective to provide a hygroscopic material typified by barium oxide in this sealed space. This hygroscopic material may be provided in contact with the sealing material, or may be provided on the partition wall or in the peripheral portion so as not to block light from the light emitting element. Further, the space between the cover material and the substrate on which the light emitting element is formed can be filled with a thermosetting resin or an ultraviolet light curable resin. In this case, it is effective to add a moisture absorbing material typified by barium oxide in the thermosetting resin or the ultraviolet light curable resin.

By using the present invention, an EL display device using a semiconductor device with high electrical characteristics can be manufactured. Therefore, a high-definition and high-quality display device can be manufactured at a low cost and with a high yield.

  An EL display device can be manufactured by using a crystalline semiconductor film manufactured according to the present invention. There are three emission modes of light emitted from an EL element: a bottom emission type, a top emission type, and a dual emission type. There is a method. In Example 5, an example of a bottom emission type that is a single-sided emission type was shown, but in this example, examples of a double-sided emission type and a top-side emission type that is a single-sided emission type are shown in FIG. 9 and FIG. explain.

  The display device illustrated in FIG. 9 is a dual emission type, and has a structure in which light is emitted from both the substrate side where the light emitting element is provided in the direction of the arrow and the sealing substrate side. Note that in this embodiment, the first electrode 910 is formed by forming a transparent conductive film and etching it into a desired shape. A transparent conductive film can be used as the first electrode 910. Further, a titanium nitride film or a titanium film may be used instead of the transparent conductive film. In this case, the titanium nitride film or the titanium film may be formed with a thickness enough to transmit light (preferably, about 5 nm to 30 nm). In this embodiment, ITSO is used as the first electrode 910.

Next, a second electrode 913 made of a conductive film is provided over the electroluminescent layer 912. The second electrode 913 may be made of a material having a low work function (Al, Ag, Li, Ca, or an alloy thereof such as MgAg, MgIn, AlLi, CaF ₂ , or CaN) in order to function as the cathode. In the display device of FIG. 9, a thin metal film (MgAg: film thickness 10 nm) is used as the second electrode 913 so that light is transmitted, and ITSO (film thickness 100 nm) which is a transparent conductive material. A laminated film is used.

  The display device illustrated in FIG. 10 is a single-sided emission type and has a structure in which the top surface is emitted in the direction of an arrow. In the dual-emission type display device illustrated in FIG. The structure is as follows. That is, as shown in FIG. 10, a first electrode 1010 that is a transparent conductive film functioning as an anode is provided over a reflective metal film 1051. Ta, W, Ti, Mo, Al, Cu, or the like may be used as the reflective metal film. In particular, it is preferable to use a substance having high reflectivity in the visible light region. In this embodiment, a TiN film is used.

A second electrode 1013 made of a conductive film is provided over the electroluminescent layer 1012. The second electrode 1013 may be formed using a material having a low work function (Al, Ag, Li, Ca, or an alloy thereof such as MgAg, MgIn, AlLi, CaF ₂ , or CaN) in order to function as the cathode. In this embodiment, as the second electrode 1013, light emission is transmitted using a laminated structure of a thin metal film (MgAg: film thickness 10 nm) and ITSO (film thickness 110 nm).

  A mode of a light-emitting element (EL light-emitting element) applicable to the present invention will be described. The light emitting element has a structure in which an electroluminescent layer is sandwiched between a first electrode and a second electrode. It is necessary to select materials for the first electrode and the second electrode in consideration of a work function, and the first electrode and the second electrode can be either an anode or a cathode depending on a pixel configuration.

  When the polarity of the TFT is a p-channel type, it is preferable that the first electrode is an anode and the second electrode is a cathode. In the case where the TFT has an N-channel polarity, it is preferable that the first electrode be a cathode and the second electrode be an anode.

  In the case where the first electrode is an anode and the second electrode is a cathode, the electroluminescent layer is formed from the first electrode (anode) side from the HIL (hole injection layer), HTL (hole transport layer), EML ( The light emitting layer), the ETL (electron transport layer), the EIL (electron injection layer), and the second electrode (cathode) are preferably laminated in this order.

  When the first electrode is a cathode and the second electrode is an anode, the electroluminescent layer is formed from the EIL (electron injection layer), ETL (electron transport layer), EML (light emission) from the first electrode (cathode) side. Layer), HTL (hole transport layer), HIL (hole injection layer), and second electrode (anode) are preferably laminated in this order.

  The light emitting layer may be configured to perform color display by forming light emitting layers having different emission wavelength bands for each pixel. Typically, a light emitting layer corresponding to each color of R (red), G (green), and B (blue) is formed. In this case, it is possible to improve color purity and prevent mirroring of the pixel part (reflection) by providing a filter that transmits light in the emission wavelength band on the light emission side of the pixel. . By providing the filter, it is possible to omit a circularly polarizing plate that has been conventionally required, and it is possible to eliminate the loss of light emitted from the light emitting layer. Furthermore, a change in color tone that occurs when the pixel portion (display screen) is viewed obliquely can be reduced.

  In addition, as the light emitting layer, materials that emit red (R), green (G), and blue (B) light are selectively formed by an evaporation method using an evaporation mask. A material that emits red (R), green (G), and blue (B) light can be formed by a droplet discharge method (such as a low-molecular or high-molecular material) in the same manner as a color filter. Even if it is not used, it is preferable because different colors of RGB can be performed.

  The light emitting layer can be configured to emit monochromatic or white light. In the case of using a white light emitting material, color display can be made possible by providing a filter (colored layer) that transmits light of a specific wavelength on the light emission side of the pixel.

  Further, a color filter (colored layer) may be formed on the sealing substrate. The color filter can be formed by a vapor deposition method or a droplet discharge method. When a color filter is used, high-definition display can be performed. This is because the color filter can correct so that a broad peak is sharp in the emission spectrum of each RGB.

  As described above, the case where a material that emits light of each RGB is formed has been described. However, full color display can be performed by forming a material that emits light of a single color and combining a color filter and a color conversion layer. For example, the color filter and the color conversion layer may be formed over a second substrate (sealing substrate) and then attached to the substrate over which the light-emitting element is formed. The color filter can be formed by a vapor deposition method or a droplet discharge method. When a color filter is used, broad peaks can be corrected in each RGB emission spectrum so that high-definition display can be performed.

  In addition to the singlet excited light emitting material, a triplet excited light emitting material containing a metal complex or the like may be used for the light emitting layer. For example, among red light emitting pixels, green light emitting pixels, and blue light emitting pixels, a red light emitting pixel having a relatively short luminance half time is formed of a triplet excitation light emitting material, and the other A singlet excited luminescent material is used. The triplet excited luminescent material has a feature that the light emission efficiency is good, so that less power is required to obtain the same luminance. That is, when applied to a red pixel, the amount of current flowing through the light emitting element can be reduced, so that reliability can be improved. As a reduction in power consumption, a red light-emitting pixel and a green light-emitting pixel may be formed using a triplet excitation light-emitting material, and a blue light-emitting pixel may be formed using a singlet excitation light-emitting material. By forming a green light-emitting element having high human visibility with a triplet excited light-emitting material, power consumption can be further reduced.

  The substances forming the light-emitting layer listed above are examples, and functional layers such as a hole injection layer, a hole transport layer, an electron injection layer, an electron transport layer, a light-emitting layer, an electron block layer, and a hole block layer are included. A light emitting layer can be formed by appropriately stacking layers. Moreover, you may form the mixed layer or mixed junction which combined these each layer. The layer structure of the light-emitting layer can be changed, and instead of having a specific electron injection region or light-emitting region, it is possible to provide a modification with an electrode for this purpose or a dispersed light-emitting material. Can be permitted without departing from the spirit of the present invention.

  The light emitting element emits light by being forward biased. A pixel of a display device formed using a light-emitting element can be driven by a simple matrix method or an active matrix method. In any case, each pixel emits light by applying a forward bias at a specific timing, but is in a non-light emitting state for a certain period. By applying a reverse bias during this non-light emitting time, the reliability of the light emitting element can be improved. The light emitting element has a degradation mode in which the light emission intensity decreases under a constant driving condition and a degradation mode in which the non-light emitting area is enlarged in the pixel and the luminance is apparently decreased. However, alternating current that applies a bias in the forward and reverse directions. By performing a typical drive, the progress of deterioration can be slowed and the reliability of the light emitting device can be improved. Further, either digital driving or analog driving can be applied.

  In the above structure, a material having a low work function can be used as the cathode, and for example, Ca, Al, CaF, MgAg, AlLi, or the like is desirable. The electroluminescent layer may be any of a single layer type, a laminated type, and a mixed type having no layer interface. For example, the electroluminescent layer may have a structure in which a hole injection layer, a hole transport layer, a hole blocking layer (hole blocking layer), a light emitting layer, an electron transport layer, an electron injection layer, and the like are appropriately combined and stacked. . In addition, the material for forming the electroluminescent layer is not limited to the organic compound alone, and may be configured to partially include an inorganic compound. These materials include low molecular weight compounds, medium molecular weight compounds ( Any of oligomers and dendrimers) and polymer compounds may be used. In addition, as a method for forming the electroluminescent layer, an evaporation method using an evaporation mask, an inkjet method, a spin coating method, or the like can be used. The first electrode is formed using a transparent conductive film that transmits light. For example, in addition to ITO and ITSO, the first electrode is formed using a transparent conductive film in which indium oxide is mixed with 2 to 20 wt% zinc oxide (ZnO).

  By using the present invention, an EL display device using a semiconductor device with high electrical characteristics can be manufactured. Therefore, a high-definition and high-quality display device can be manufactured at a low cost and with a high yield.

  This example can be combined with any of the embodiment mode and Examples 1 to 6 as appropriate.

  In this embodiment, the appearance of a liquid crystal display device panel, which is one embodiment of the semiconductor device of the present invention, will be described with reference to FIGS. FIG. 13A is a top view of a panel in which a space between the first substrate 1600 and the second substrate 1604 is sealed with the first sealant 1605 and the second sealant 1606. FIG. FIG. 13B corresponds to a cross-sectional view taken along lines AA ′ and BB ′ in FIG.

  In FIG. 13A, 1601 indicated by a dotted line is a signal line (source line) driver circuit, 1602 is a pixel portion, and 1603 is a scanning line (gate line) driver circuit. In this embodiment, the pixel portion 1602 and the scan line driver circuit 1603 are in a region sealed with a first sealant 1605 and a second sealant 1606. In addition, the signal line (source line) driver circuit 1601 has a chip shape and is provided over the first substrate 1600. Each of the signal line driver circuit 1601, the pixel portion 1602, and the scan line driver circuit 1603 includes a plurality of semiconductor elements typified by TFTs.

  Next, a cross-sectional structure will be described with reference to FIG. A signal line driver circuit 1601, a pixel portion 1602, and a scan line driver circuit 1603 are formed over the first substrate 1600. Further, a color filter (not shown) is provided on the surface of the second substrate 1604. In this cross-sectional view, a scan line driver circuit 1603 and a pixel portion 1602 are shown. Note that the scan line driver circuit 1603 may be formed with a CMOS circuit in which an n-channel TFT 1612 and a p-channel TFT 1613 are combined, or may be formed with only one of an n-channel TFT or a p-channel TFT. Good.

  In this embodiment, the scanning line driving circuit and the TFT of the pixel portion are formed on the same substrate. For this reason, the volume of the display device can be reduced.

  In the pixel portion 1601, a plurality of pixels are formed, and a liquid crystal element 1615 is formed in each pixel. The liquid crystal element 1615 is a portion where the first electrode 1616, the second electrode 1618, and the liquid crystal material 1619 filled therebetween overlap. A first electrode 1616 included in the liquid crystal element 1615 is electrically connected to the TFT 1611 through a wiring 1617. Although the first electrode 1616 is formed after the wiring 1617 is formed here, the wiring 1617 may be formed after the first electrode 1616 is formed as shown in Embodiment 1. The second electrode 1618 of the liquid crystal element 1615 is formed on the second substrate 1604 side. Further, although not shown, an alignment film is formed on the surface of each pixel electrode.

  Reference numeral 1622 denotes a columnar spacer, which is provided to control the distance (cell gap) between the first electrode 1616 and the second electrode 1618. The insulating film is formed by etching into a desired shape. A spherical spacer may be used. Various signals and potentials supplied to the signal line driver circuit 1601 or the pixel portion 1602 are supplied from the FPC 1609 through the connection wiring 1623. Note that the connection wiring 1623 and the FPC 1609 are electrically connected by an anisotropic conductive film or an anisotropic conductive resin 1627. Note that a conductive paste such as solder may be used instead of the anisotropic conductive film or the anisotropic conductive resin 1627.

  A polarizing plate 1625 is fixed to the surface of the second substrate 1604 with an adhesive 1624. Note that a circularly polarizing plate or an elliptically polarizing plate provided with a retardation plate may be used for the polarizing plate 1625. Further, a 1 / 2λ or 1 / 4λ phase difference plate 1629 and an antireflection film 1626 are provided on the surface of the polarizing plate 1625. Similarly, a polarizing plate is provided on the surface of the first substrate 1600 with an adhesive.

  In this embodiment, the appearance of an EL display panel corresponding to one embodiment of the semiconductor device of the present invention will be described with reference to FIGS. 14A is a top view of a panel in which a space between the first substrate 1400 and the second substrate 1404 is sealed with the first sealant 1405 and the second sealant 1406. FIG. FIG. 14B corresponds to a cross-sectional view taken along line AA ′ in FIG.

  In FIG. 14A, 1402 indicated by a dotted line is a pixel portion, and 1403 is a scanning line (gate line) driver circuit. In this embodiment, the pixel portion 1402 and the scan line driver circuit 1403 are in a region sealed with a first sealant 1405 and a second sealant 1406. Reference numeral 1401 denotes a signal line (source line) driver circuit, and a chip-like signal line driver circuit 1401 is provided on the first substrate 1400. As the first sealant 1405, it is preferable to use a highly viscous epoxy resin containing a filler. In addition, as the second sealing material 1406, it is preferable to use an epoxy resin having low viscosity. In addition, the first sealing material 1405 and the second sealing material 1406 are desirably materials that do not transmit moisture and oxygen as much as possible. Each of the signal line driver circuit 1401, the pixel portion 1402, and the scan line driver circuit 1403 includes a plurality of semiconductor elements typified by TFTs.

Further, a desiccant may be provided between the pixel portion 1402 and the sealant 1405. Further, in the pixel portion 1402, a desiccant may be provided over the scan line or the signal line. As the desiccant, it is preferable to use a substance that adsorbs water (H ₂ O) by chemical adsorption such as an oxide of an alkaline earth metal such as calcium oxide (CaO) or barium oxide (BaO). However, the substance is not limited to these substances, and a substance that adsorbs water by physical adsorption such as zeolite or silica gel may be used.

  In addition, the resin can be fixed to the second substrate 1404 in a state where a highly moisture-permeable resin contains a granular material of a desiccant. Further, siloxane, polyimide, PSG (phosphorus glass), BPSG (phosphorus boron glass), or the like may be used instead of a highly moisture-permeable resin.

  Further, a desiccant may be provided in a region overlapping with the scanning line. Furthermore, you may fix to the 2nd board | substrate in the state which included the granular substance of the desiccant in resin with high moisture permeability. By providing these desiccants, it is possible to suppress the intrusion of moisture into the display element and the deterioration caused thereby without reducing the aperture ratio. For this reason, it is possible to suppress variation in deterioration of the light emitting elements in the peripheral portion and the central portion of the pixel portion 1402.

  Reference numeral 1410 denotes a connection region for transmitting signals input to the signal line driver circuit 1401 and the scanning line driver circuit 1403. The flexible printed wiring 1409 (FPC) serving as an external input terminal is connected via a connection wiring 1408. Receive video and clock signals.

  Next, a cross-sectional structure is described with reference to FIG. A signal line driver circuit 1401, a pixel portion 1402, and a scan line driver circuit 1403 are formed over the first substrate 1400. In this cross-sectional view, a signal line driver circuit 1401 and a pixel portion 1402 are shown. Note that as the signal line driver circuit 1401, a CMOS circuit in which an n-channel TFT 1421 and a p-channel TFT 1422 are combined is formed.

  In this embodiment, the scanning line driving circuit and the TFT of the pixel portion are formed on the same substrate. For this reason, the volume of the light emitting display device can be reduced.

  The pixel portion 1402 includes a switching TFT 1411, a plurality of first pixel electrodes (anodes) 1413 made of a light-transmitting conductive film electrically connected to the driving TFT 1412 and its drain (or source). It is formed by pixels. Note that the switching TFT 1411 is a TFT provided to select whether or not to input a signal to the pixel, and the driving TFT 1412 is a TFT provided to drive the light emitting element.

  In addition, insulators (referred to as banks, partition walls, barriers, banks, or the like) 1414 are formed at both ends of the first pixel electrode (anode) 1413. In order to improve the coverage (coverage) of the film formed over the insulator 1414, a curved surface having a curvature is formed at the upper end portion or the lower end portion of the insulator 1414. The surface of the insulator 1414 may be covered with an aluminum nitride film, an aluminum nitride oxide film, a thin film containing carbon as its main component, or a protective film made of a silicon nitride film. Further, by using an organic material in which a material that absorbs visible light such as a black pigment or a dye is used as the insulator 1414, stray light from a light-emitting element to be formed later can be absorbed. As a result, the contrast of each pixel is improved.

  Further, an organic compound material is deposited on the first pixel electrode (anode) 1413 to selectively form an electroluminescent layer 1415. Further, a second pixel electrode (cathode) 1416 is formed over the electroluminescent layer 1415.

  Thus, a light-emitting element 1417 including the first pixel electrode (anode) 1413, the electroluminescent layer 1415, and the second pixel electrode (cathode) 1416 is formed. In this embodiment, light emitted from the light emitting element 1417 is emitted to the first substrate 1400 side. However, the configuration is not limited thereto, and the light may be emitted to the second substrate 1404 side, or may be emitted from both sides of the first substrate 1400 and the second substrate 1404.

  In addition, a protective stack 1418 is formed to seal the light-emitting element 1417. The protective laminate 1418 includes a laminate of a first inorganic insulating film, a stress relaxation film, and a second inorganic insulating film. Next, the protective laminate 1418 and the second substrate 1404 are bonded with a first sealant 1405 and a second sealant 1406. Note that the second sealant is preferably dropped using a device for dropping the sealant. After the sealing material is dropped or discharged from the dispenser to apply the sealing material onto the active matrix substrate, the second substrate and the active matrix substrate are bonded together in a vacuum and then cured by ultraviolet curing. it can.

  Note that an antireflection film 1426 is provided on the surface of the second substrate 1404 to prevent external light from being reflected from the surface of the substrate. In addition, one or both of the polarizing plate 1425 and the retardation film 1429 may be provided between the second substrate 1404 and the antireflection film 1426. By providing the retardation plate and the polarizing plate, it is possible to prevent external light from being reflected by the pixel electrode. Note that the first pixel electrode 1413 and the second pixel electrode 1416 are formed using a light-transmitting conductive film or a semi-transparent conductive film, and absorb visible light or a material that absorbs visible light. When the insulator 1414 is formed using an organic material in which the material is dissolved or dispersed, external light is not reflected by each pixel electrode, so that a retardation plate and a polarizing plate are not necessarily used.

  The connection wiring 1408 and the flexible printed wiring 1409 are electrically connected by an anisotropic conductive film or anisotropic conductive resin 1427. Furthermore, it is preferable to seal the connection portion between each wiring layer and the connection terminal with a sealing resin. With this structure, moisture from the cross section can be prevented from entering and deteriorating the light emitting element.

  Note that a space filled with an inert gas such as nitrogen gas may be provided between the second substrate 1404 and the protective stack 1418 instead of the second sealant 1406. It is possible to enhance prevention of moisture and oxygen from entering.

  In addition, a colored layer can be provided between the second substrate and the polarizing plate 1425. In this case, a full color display can be performed by providing a light emitting element capable of emitting white light in the pixel portion and separately providing a colored layer showing RGB. Further, full color display can be performed by providing a light emitting element capable of emitting blue light in the pixel portion and separately providing a color conversion layer or the like. Further, a light-emitting element that emits red, green, and blue light can be formed in the pixel portion, and a colored layer can be used. Such a display module has a high color purity of each RGB and enables high-definition display.

  Alternatively, the light-emitting display module may be formed using one of the first substrate 1400 and the second substrate 1404, or a substrate such as a film or resin. When sealing is performed without using the counter substrate in this manner, the weight, size, and thickness of the display device can be improved.

  Furthermore, an IC chip such as a controller, a memory, and a pixel driver circuit may be provided on the surface or end of the flexible printed wiring 1409 (FPC) serving as an external input terminal to form a light emitting display module.

  As an electronic device using a semiconductor device manufactured according to the present invention, a video camera, a digital camera, a goggle type display (head mounted display), a navigation system, a sound reproduction device (car audio, audio component, etc.), a computer, a game device, a mobile phone An information terminal (mobile computer, mobile phone, portable game machine, electronic book, etc.), an image playback device (specifically, a DVD (digital versatile disc)) provided with a recording medium, and the image is displayed. A device provided with a display capable of display), and other appliances having a display portion. In addition, if a crystalline semiconductor film formed by the laser irradiation method of the present invention is used, an integrated circuit that requires extremely high characteristics, such as a CPU and a memory, can be manufactured. A specific example of the electronic device is illustrated in FIG.

  FIG. 15A illustrates a television receiver which includes a housing 2001, a support base 2002, a display portion 2003, a speaker portion 2004, a video input terminal 2005, and the like. As shown in the embodiment, a television receiver can be manufactured by using a semiconductor device with high electrical characteristics obtained by laser light irradiation for the display portion 2003 or the like.

  FIG. 15B illustrates a digital camera, which includes a main body 2101, a display portion 2102, an image receiving portion 2103, operation keys 2104, an external connection port 2105, a shutter 2106, and the like. As shown in the embodiment, a digital camera can be manufactured by using a semiconductor device with high electrical characteristics obtained by laser light irradiation for the display portion 2102 and other circuits.

  FIG. 15C illustrates a computer, which includes a main body 2201, a housing 2202, a display portion 2203, a keyboard 2204, an external connection port 2205, a pointing mouse 2206, and the like. As shown in the embodiment, a computer can be manufactured by using a semiconductor device with high electrical characteristics obtained by laser light irradiation for the display portion 2203 and other circuits.

  FIG. 15D illustrates a mobile computer, which includes a main body 2301, a display portion 2302, a switch 2303, operation keys 2304, an infrared port 2305, and the like. As described in the embodiment, a mobile computer can be manufactured by using a semiconductor device with high electrical characteristics obtained by laser light irradiation for the display portion 2302 and other circuits.

  FIG. 15E illustrates a portable image reproducing device (such as a DVD reproducing device) provided with a recording medium. The main body 2401, a housing 2402, a display portion A2403, a display portion B2404, and a recording medium (DVD or the like) reading portion 2405 Operation key 2406, speaker unit 2407, and the like. A display portion A2403 mainly displays image information, and a display portion B2404 mainly displays character information. As shown in the embodiment, an image reproducing device can be manufactured by using a semiconductor device with high electrical characteristics obtained by laser light irradiation for the display portion A 2403, the display portion B 2404, or other circuits. it can. Note that the image reproducing device provided with the recording medium includes a game machine and the like.

  FIG. 15F illustrates a goggle type display (head mounted display), which includes a main body 2501, a display portion 2502, and an arm portion 2503. As shown in the embodiment, a goggle type display can be manufactured by using a semiconductor device with high electrical characteristics obtained by laser light irradiation for the display portion 2502 and other circuits.

  FIG. 15G illustrates a video camera, which includes a main body 2601, a display portion 2602, a housing 2603, an external connection port 2604, a remote control reception portion 2605, an image receiving portion 2606, a battery 2607, an audio input portion 2608, operation keys 2609, and an eyepiece. Part 2610 and the like. As shown in the embodiment, a video camera can be manufactured by using a semiconductor device with high electrical characteristics obtained by laser light irradiation for the display portion 2602 and other circuits.

  FIG. 15H illustrates a cellular phone, which includes a main body 2701, a housing 2702, a display portion 2703, an audio input portion 2704, an audio output portion 2705, operation keys 2706, an external connection port 2707, an antenna 2708, and the like. As shown in the embodiment, a mobile phone can be manufactured by using a semiconductor device with high electrical characteristics obtained by laser light irradiation for the display portion 2703, other circuits, or the like.

  In addition to the electronic devices described above, the projector can be used for a front or rear projector.

  As described above, the applicable range of the present invention is so wide that the present invention can be used for electronic devices and integrated circuits in various fields.

The figure which shows the best form for implementing this invention. The figure which shows Example 1 of this invention. The figure which shows the reflectance of a reflecting film. The figure which shows Example 1 of this invention. The figure which shows Example 1 of this invention. The figure which shows Example 2 of this invention. The figure which shows Example 3 of this invention. The figure which shows Example 5 of this invention. The figure which shows Example 6 of this invention. The figure which shows Example 6 of this invention. The figure which shows Example 4 of this invention. The figure which shows Example 4 of this invention. The figure which shows Example 8 of this invention. The figure which shows Example 9 of this invention. The figure which shows Example 10 of this invention. The figure which shows the example of a structure of a reflecting film.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Insulating substrate 102 Base film 103 Amorphous semiconductor film 104 Reflective film 105 Crystalline semiconductor film 110 The area | region where the semiconductor film is covered with the reflective film 111 The area | region where the semiconductor film was exposed

Claims (14)

Forming a semiconductor film on an insulating substrate;
Forming a reflective film made of an insulating film on a part of the semiconductor film;
A method for manufacturing a semiconductor device, wherein the exposed semiconductor film is crystallized by irradiating laser light with the reflective film as a mask. Forming a semiconductor film on an insulating substrate;
Forming a reflective film made of an insulating film on the semiconductor film;
Patterning the reflective film to expose a portion of the semiconductor film;
A method for manufacturing a semiconductor device, wherein the exposed semiconductor film is crystallized by irradiating a laser beam with the patterned reflective film as a mask. Forming a base film on an insulating substrate;
Forming a semiconductor film on the base film;
Forming a reflective film made of an insulating film on the semiconductor film;
Patterning the reflective film to expose a portion of the semiconductor film;
By irradiating a laser beam using the patterned reflective film as a mask, the exposed semiconductor film is crystallized,
Removing the patterned reflective film;
Patterning a portion of the semiconductor film;
Forming a gate insulating film on the patterned semiconductor film;
Forming a gate electrode on the gate insulating film;
A method for manufacturing a semiconductor device, wherein the crystallized semiconductor film is used for a channel formation region of a thin film transistor. Forming a base film on an insulating substrate;
Forming a semiconductor film on the base film;
Irradiating the semiconductor film with a first laser beam;
A reflective film made of an insulating film is formed on the semiconductor film irradiated with the first laser beam,
Patterning the reflective film to expose a portion of the semiconductor film;
A method for manufacturing a semiconductor device, wherein the exposed semiconductor film is crystallized by irradiating a second laser beam using the patterned reflective film as a mask. Forming a base film on an insulating substrate;
Forming a semiconductor film on the base film;
Irradiating the semiconductor film with a first laser beam to form a crystalline semiconductor film;
Forming a reflective film made of an insulating film on the crystalline semiconductor film;
Patterning the reflective film to expose a portion of the crystalline semiconductor film;
Irradiation with a second laser beam using the patterned reflective film as a mask improves the crystallinity of the exposed semiconductor film while maintaining the orientation of the crystalline semiconductor film. A method for manufacturing a semiconductor device.   6. The method for manufacturing a semiconductor device according to claim 4, wherein the semiconductor film provided under the reflective film is not melted by irradiation with the second laser light.   7. The method for manufacturing a semiconductor device according to claim 4, wherein the reflective film reflects the second laser beam.   8. The method for manufacturing a semiconductor device according to claim 2, wherein the reflective film is patterned by dry etching.   9. The method for manufacturing a semiconductor device according to claim 2, wherein the patterned reflective film is removed by wet etching.   10. The semiconductor film according to claim 2, wherein the semiconductor film is laterally crystallized from a region of the semiconductor film provided under the patterned reflective film toward a direction of the exposed semiconductor film region. A method for manufacturing a semiconductor device, characterized by growing.   11. The method for manufacturing a semiconductor device according to claim 10, wherein the thin film transistor is formed so that a carrier moving direction in the channel formation region of the thin film transistor is parallel to the crystal growth direction in the lateral direction.   12. The method for manufacturing a semiconductor device according to claim 1, wherein the reflective film includes a silicon oxide film and a silicon nitride film formed in contact with the silicon oxide film.   13. The method for manufacturing a semiconductor device according to claim 1, wherein the semiconductor device is any one of a liquid crystal display device, an EL display device, and an integrated circuit. 14. The semiconductor device according to claim 13, wherein the semiconductor device is used for any one of a video camera, a digital camera, a navigation system, an audio playback device, a computer, a game machine, a portable information terminal, and an image playback device. Method.

Images