JP5094099B2 - Method for manufacturing semiconductor device - Google Patents

Description

  The present invention relates to a technique for forming a semiconductor film having a crystal structure by irradiating a semiconductor film with a laser beam, and a method for manufacturing a semiconductor device such as a thin film transistor using the semiconductor film having a crystal structure formed by using this technique.

  In recent years, a laser crystallization technique for forming a semiconductor film having a crystal structure (hereinafter referred to as a crystalline semiconductor film) by irradiating an amorphous semiconductor film formed over a glass substrate with a laser beam has been widely studied. The crystalline semiconductor film is used because it has higher field-effect mobility than an amorphous semiconductor film. The crystalline semiconductor film on the glass substrate is, for example, an active matrix liquid crystal display device or an organic EL display device in which thin film transistors for a pixel portion or for a pixel portion and a drive circuit are formed on a single glass substrate. Etc. are used.

  Examples of the crystallization method include a thermal annealing method using a furnace annealing furnace, an instantaneous thermal annealing method (RTA method), a laser annealing method (crystallization method by laser irradiation), and the like, such as a thermal annealing method. In the case of using the solid phase growth method, a high-temperature treatment at 600 ° C. or higher is required, so that an expensive quartz substrate that can withstand the high heat is required, which increases the manufacturing cost. On the other hand, when a laser is used for crystallization, it is possible to crystallize by absorbing heat only in the semiconductor film without increasing the temperature of the substrate so much, so that the substrate has a low melting point such as glass or plastic. Can be used.

  One laser annealing method is a crystallization method using an excimer laser which is a pulse laser. The wavelength of the excimer laser belongs to the ultraviolet region and has a high absorption rate for silicon. Therefore, when an excimer laser is used, most of the laser beam can be absorbed by silicon. For example, in excimer laser annealing, a rectangular beam spot of about 10 mm × 30 mm emitted from an excimer laser is processed into a linear beam spot having a width of several hundreds μm and a length of 300 mm or more by an optical system. The silicon film is crystallized by irradiating the linearly processed beam spot while scanning the silicon film on the substrate relatively. In the present specification, a rectangular shape or an elliptical shape having a high aspect ratio (10 or more) is called a linear shape.

  As another laser annealing method, there are a crystallization method using a continuous wave laser (hereinafter referred to as “CW laser”; CW: continuous-wave) laser and a pulse laser having a repetition frequency of 10 MHz or higher. Even in the laser annealing using these lasers, the beam emitted from the laser is converted into a linear beam spot, and the silicon film is irradiated while scanning the linear beam spot to crystallize the silicon film. Since a silicon film can be completely melted and crystallized by using a CW laser or the like, the crystallinity having a crystal region having a very large grain size (hereinafter referred to as a large grain crystal) compared to excimer laser annealing. A silicon film can be formed (see, for example, Patent Document 1). This is because excimer laser annealing crystallizes due to accidental nucleation generated at the silicon film and its underlying interface, whereas in laser annealing such as CW laser, a solid-liquid interface is obtained by scanning a linear beam spot. This is because the crystal can be laterally grown.

When this large grain crystal is used in the channel formation region of the thin film transistor, the crystal grain boundary is hardly included in the channel direction, and the energy wall for carriers such as electrons and holes is lowered. Therefore, a thin film transistor having a field effect mobility of 100 cm ² / Vs or more can be manufactured.
JP 2005-191546 A

  Thin film transistors are also required to be miniaturized, like MOS transistors formed on silicon wafers. For that purpose, it is necessary to make the silicon film which becomes the channel formation region of the thin film transistor thin to 40 nm or less. However, it is very difficult to form a large grain crystal in a silicon film having a thickness of 40 nm or less by laser beam irradiation.

  The crystal structure of the crystalline silicon film crystallized by irradiation with the laser beam depends on the energy of the laser beam. As the energy of the laser beam increases, the crystal structure changes to a microcrystal, a small grain crystal, and a large grain crystal. It has been found that forming a large grain crystal requires energy to completely melt the amorphous silicon film. Of course, if the energy of the laser beam is too large, the silicon film will be broken (split) or ablated.

  FIG. 15 shows the film thickness dependence of the reflectance, transmittance, and absorptance of the amorphous silicon film with respect to light having a wavelength of 532 nm. The horizontal axis of the graph of FIG. 15 represents the thickness of the amorphous silicon film, and the vertical axis represents a ratio such as reflectance. As is apparent from FIG. 15, when the thickness of the amorphous silicon film is 50 nm or less, the absorptance decreases as the film thickness decreases, and the amount of light reflected or transmitted by the amorphous silicon film is reduced. Will be more. The absorptance when the thickness is 20 nm is about １ ／ that when the thickness is 50 nm, and the transmittance is twice or more.

  Therefore, as in the case of crystallizing an amorphous silicon film having a thickness of 50 nm, if a large grain crystal is formed from an amorphous silicon film having a thickness of 20 nm, the energy of the laser beam is made extremely high. There is a need. Therefore, the laser is oscillated at a high output, and the life of the laser medium is shortened. Further, since high energy is applied to the amorphous silicon film, it is very difficult to optimize the energy of the laser beam, and ablation is likely to occur.

  In view of the above-described problems, the present invention provides a method for forming a large grain crystal in a very thin semiconductor film having a thickness of 40 nm or less by irradiation with a laser beam.

  The present invention melts a semiconductor film by making a laser beam incident not only from the upper surface of the semiconductor film but also from a side surface. Therefore, a structure having a reflection surface for allowing a beam irradiated from above the semiconductor film to enter the side surface is formed.

  The laser beam is irradiated from above the semiconductor film, and the laser beam is reflected by the reflecting surface of the structure, so that the laser beam is incident on the semiconductor film from the side surface. The reflecting surface may be made of a material such as metal that has a high reflectance (80% or more) with respect to the laser beam and a low transmittance and absorptance. That is, the structure is caused to function as a reflection mirror. In addition, the structure is made of a material that has a refractive index higher than that of the air and transmits the laser beam, so that the laser beam is totally reflected at the interface between the reflecting surface and air while allowing the structure to pass the laser beam. You can also. That is, the structure is caused to function as a prism.

  The present invention has been made by paying attention to the fact that the refractive index of silicon, which is a typical example of a semiconductor, is as large as about 4. The refractive index of the semiconductor film is larger than the refractive index of a medium (for example, air or an insulating surface) with which the semiconductor film is in contact. Therefore, according to Snell's law, most of the laser beam incident from the side surface of the semiconductor film propagates through the semiconductor film while repeating total reflection in the semiconductor film. As a result, the semiconductor film can be completely melted with the laser beam, and a large grain crystal can be formed. Note that the completely melted state means a state in which the semiconductor film is melted from the upper surface to the interface with the insulating surface, or a liquid state.

  As described above, in order to form a large grain crystal, the semiconductor film is completely melted by laser beam irradiation. Therefore, a continuous wave laser or a pseudo continuous wave laser is preferably used as the laser. Even in the case of a pulsed laser, if the oscillation frequency is 10 MHz or more, the semiconductor film can be completely melted by laser beam irradiation as in the case of a continuous wave laser.

The wavelength of the laser beam is determined in consideration of the skin depth of the laser beam and the thickness of the semiconductor film to be crystallized. In order to completely melt the semiconductor film and obtain a large grain crystal, it is preferable to use a continuous wave laser or a pseudo continuous wave laser with a laser beam wavelength in the range of 400 nm to 565 nm. For example, the laser beam in this wavelength region includes the second harmonic (532 nm) of the YVO ₄ laser, the second harmonic (532 nm) of the YAG laser, and the second harmonic (527 nm) of the YLF laser. The exemplified YVO ₄ laser can be a continuous wave laser, a pulsed laser, or a pseudo continuous wave laser.

  The crystal structure of the semiconductor film before the laser beam irradiation may be a non-single crystal. For example, amorphous, microcrystalline, and polycrystalline structures. The semiconductor film is a semiconductor film containing silicon or germanium as a main component. For example, a silicon film, a germanium film, or a compound film of silicon and germanium. The semiconductor film may contain an n-type impurity such as P (phosphorus) and As (arsenic) and a p-type impurity such as B (boron).

  Examples of the substrate on which the semiconductor film and the structure are formed include a substrate made of an insulating material such as a glass substrate, a quartz substrate, a sapphire substrate, and a plastic substrate, a conductive substrate such as a stainless steel substrate, and a semiconductor substrate. In the case of using a conductive substrate such as a stainless steel substrate and a semiconductor substrate, an insulating film may be formed on the upper surface, and the semiconductor film may be formed on the insulating film. In the case of using a substrate containing a substance that contaminates the semiconductor film, such as a glass substrate or a plastic substrate, it is preferable to cover the upper surface with an insulating film so that the semiconductor film is not contaminated. Further, forming the insulating film thickly has an effect of making it difficult to transfer heat to the substrate. As the insulating film formed over the top surface of the substrate, a single layer film or a stacked film of silicon oxide, silicon nitride, silicon oxynitride, or the like can be used. These insulating films can be formed by a CVD method or a sputtering method.

  In the present invention, since the laser beam is incident not only from the upper surface but also from the side surface of the semiconductor film, even a semiconductor film having a film thickness of 40 nm or less can be completely melted. As a result, a large grain crystal can be formed in a thin semiconductor film of 40 nm or less. In addition, the energy of the laser beam required for complete melting can be lower than when the laser beam is incident only from the upper surface and completely melted, so there is less burden on the laser and it is easy to optimize the energy of the laser beam. Become.

  By forming a channel formation region using a large grain crystal obtained by the crystallization method of the present invention, a thin film transistor with high field effect mobility can be manufactured. In addition, since the channel formation region can be thinned to 40 nm or less, the power consumption of the thin film transistor can be reduced. By forming an integrated circuit using such a thin film transistor, a high-performance and multifunctional semiconductor device with low power consumption can be manufactured.

  The present invention will be described below with reference to the drawings. However, the present invention can be implemented in many different modes, and it is easy for those skilled in the art to make various changes in form and details without departing from the spirit and scope of the present invention. To be understood. Therefore, the present invention should not be construed as being limited to the description of the embodiment modes.

(Embodiment 1)
In this embodiment mode, a method in which a laser beam is incident from a side surface of a semiconductor film with a structure having a reflective surface will be described.

  A method for crystallizing a semiconductor film will be described with reference to FIGS. 1 is a cross-sectional view taken along line x-x ′ of FIG. 2. An insulating film 11 is formed on the substrate 10. A semiconductor film 12 and a structure 13 that functions as a mirror are formed adjacent to the semiconductor film 12 on the surface of the insulating film 11.

  The semiconductor film 12 is selectively formed on the insulating film 11 so as to have a side surface 12a for allowing the laser beam 14 to enter. In other words, the semiconductor film 12 is formed to have a flat surface (side surface 12a) that is not parallel to the surface of the insulating film 11 or the substrate 10. For example, as shown in FIG. 2, the semiconductor film 12 is formed on the insulating film 11 in a band shape or an island shape. Note that the side surface 12 a of the semiconductor film 12 may not be perpendicular to the surface of the substrate 10. The inclined angle of the side surface 12a may be less than 90 °, and the semiconductor film 12 may be provided with a tapered portion.

  The structure 13 has a tapered portion 13b. The inclined side surface of the tapered portion 13b is the reflecting surface 13a. The reflection surface 13 a faces the side surface 12 a of the semiconductor film 12. In order to reflect the laser beam 14 on the reflecting surface 13a, the structure 13 is made of a material having a high reflectance with respect to the wavelength of the laser beam. For example, it is made of a metal such as aluminum, titanium, or chromium. Alternatively, the main body of the structure body 13 is formed of an insulating film such as a silicon oxide film, a silicon oxynitride film, or a silicon nitride film, and at least the surface of the portion that becomes the reflective surface 13a is laser-like like a metal such as aluminum, titanium, or chromium. The structure 13 can also be formed by covering with a material having a high reflectance with respect to the wavelength of the beam.

The inclination angle theta ₁ of the reflecting surface 13a has a 45 ° but ideally in the range of 45 ° ± 30 °, is determined according to the distance of the side surface 12a of the reflecting surface 13a and the semiconductor film 12. In order to make the laser beam 14 efficiently enter from the side surface 12 a of the semiconductor film 12, the thickness of the structure 13 is set to be equal to or greater than the thickness of the semiconductor film 12.

  Further, the reflecting surface 13a may be a parabolic surface instead of a flat surface, and the laser beam 14 may be condensed on the side surface 12a of the semiconductor film 12.

  Since the laser beam 14 emitted from the oscillator has a spot shape, the laser beam 14 is shaped to be linear on the illuminated surface by an optical system including a cylindrical lens. As indicated by the arrows in FIG. 2, the laser beam 14 is irradiated from above the semiconductor film 12 and the structure 13 while scanning the linear laser beam 14 in a direction parallel to the short direction. The laser beam 14 is reflected by the reflecting surface 13 a of the structure 13 and enters the semiconductor film 12 from the side surface 12 a. According to Snell's law, the laser beam 14 propagates through the semiconductor film 12 while being totally reflected at the interface between the semiconductor film 12 and air and at the interface between the semiconductor film 12 and the insulating film 11. This is because the refractive index of the semiconductor film 12 is much larger than that of air and the insulating film 11. The refractive index of silicon, which is a typical example of the semiconductor film 12, is about 4, germanium is about 3, the refractive index of air is about 1, and the refractive index of the silicon oxide film used for the insulating film 11 is about 1. 4.

  If the laser beam 14 can be incident on the inside of the semiconductor film 12 from the side surface 12 a, most of the laser beam 14 is totally reflected at the interface between the upper surface of the semiconductor film 12 and air and the interface between the lower surface of the semiconductor film 12. Can be confined in the semiconductor film 12. Therefore, even when the laser beam 14 is irradiated from above, the semiconductor film 12 having a film thickness of 40 nm or less can be completely melted to form the crystalline semiconductor 15 having a large grain crystal in the semiconductor film 12. Become.

  In order to make the laser beam 14 efficiently enter the semiconductor film 12, it is preferable to provide the structures 13 adjacent to the pair of side surfaces 12a facing each other. In this case, as shown in FIG. 2, the region to be irradiated with the laser beam 14 is disposed so as to include the reflecting surfaces 13 a of the two structures 31 adjacent to the semiconductor film 12.

  Considering the attenuation of the laser beam 14 inside the semiconductor film 12, when the laser beam 14 is incident from one side surface 12a, the semiconductor film 12 is completely melted from the side surface 12a to about 200 nm to 300 nm. As shown in FIG. 1, when two structures 13 are provided with the semiconductor film 12 interposed therebetween, the upper limit of the distance d (width d of the semiconductor film 12) between the opposing side surfaces 12a is set to about 500 nm. The entire semiconductor film 12 in the irradiated region of the beam 14 can be completely melted.

  Further, as shown in FIG. 3, the laser beam 14 can be irradiated with the surface of the semiconductor film 12 covered with the insulating film 16. The insulating film 16 is a silicon oxide film, a silicon oxynitride film, a single layer film of a silicon nitride film, or a multilayer film of these films. Since the refractive index of the semiconductor film 12 is higher than that of the insulating film 16, even if the laser beam 14 is irradiated in a state of covering the insulating film 16, the laser beam 14 incident from the side surface 12 a is incident on the insulating film 11 and the semiconductor film. Therefore, the laser beam 14 can be confined inside the semiconductor film 12. Therefore, the semiconductor film 12 can be completely melted to form a crystalline semiconductor film having a large grain crystal.

(Embodiment 2)
In this embodiment mode, a method in which a laser beam is incident from a side surface of a semiconductor film with a structure functioning as a prism will be described.

  A method for crystallizing a semiconductor film will be described with reference to FIG. In the figure, the same reference numerals as those in FIG. 1 denote the same elements, and repeated description is omitted. In this embodiment, a structure 31 that functions as a prism is formed instead of the structure 13 that functions as a mirror.

  As shown in FIG. 4A, the structure 31 that functions as a prism is formed on the surface (insulating surface) of the insulating film 11 adjacent to the side surface 12 a of the semiconductor film 12. FIG. 4A shows an example in which two structures 31 are formed.

  The structure 31 has a reverse tapered portion 31b (a portion surrounded by a dotted line in FIG. 4A) in which the reflection surface 31a is inclined in order to deflect the optical path of the laser beam 14 incident from the upper surface by the reflection surface 31a. The reflection surface 31 a is formed to face the side surface 12 a of the semiconductor film 12. In FIG. 4, the side surface of the structure 31 that faces the reflecting surface 31 a is provided away from the side surface 12 a of the semiconductor film 12. The beam 14 can be incident.

In order to make the structure 31 function as a prism, the structure 31 is formed of a material having a high transmittance with respect to the laser beam 14 and a refractive index larger than that of air. For example, the structure 31 can be formed using silicon oxide, silicon oxynitride, or the like. The inclination angle theta ₂ of the inverse tapered portion 31b in order to correspond to the apex angle of the prism, but 45 ° is ideal, depending on the distance of the reflecting surface 31a of the side surface 12a and the structure 31 of the semiconductor film 12 The inclination angle θ ₂ can be determined within a range of 45 ° ± 30 °. Further, the thickness of the inversely tapered portion 31 b of the structure 31 is made larger than that of the semiconductor film 12 in order to make the laser beam 14 efficiently enter the side surface 12 a of the semiconductor film 12. Further, the reverse taper portion 31 b is formed to a thickness that does not melt by the laser beam 14.

  Irradiation is performed from above the semiconductor film 12 and the structure 31 while scanning with the laser beam 14. The laser beam 14 incident on the upper surface of the structure 31 is reflected at the interface between the reflecting surface 31a and the air, and its optical path is deflected. The laser beam reflected by the reflecting surface 31a is emitted from the side surface of the structure 31 and enters the semiconductor film 12 from the side surface 12a. The incident laser beam 14 propagates through the semiconductor film 12 while being totally reflected at the interface between the upper surface of the semiconductor film 12 and air and at the interface between the lower surface of the semiconductor film 12 and the insulating film 11. The semiconductor film 12 absorbs the laser beam 14 and is completely melted to become a large grain crystal.

  In order for the structure 31 to function as a prism, it is sufficient to have at least a right triangular prism-like portion (corresponding to the reverse tapered portion 31b in FIG. 4A). Further, in order to make the laser beam 14 incident from the side surface 12a of the semiconductor film 12, this right triangular prism portion is formed on the insulating film 11 and arranged as shown in FIG. That is, in the right triangular prism, the surface including one side of the two sides other than the oblique side is disposed in parallel with the insulating surface, and the surface including the other side is disposed to face the side surface 12 a of the semiconductor film 12. Thus, the surface including the hypotenuse of the right triangle is inclined and is opposed to the side surface 12 a of the semiconductor film 12.

  As described above, by providing the structure functioning as a prism, the semiconductor film having a thickness of 40 nm or less can be completely melted even when the laser beam is irradiated from above the semiconductor film 12. It is possible to form a crystalline semiconductor film having a large crystal grain size of 40 nm or less.

(Embodiment 3)
In this embodiment, a method for forming a structure film functioning as a mirror and a semiconductor film having side surfaces will be described.

  First, a method for forming a semiconductor film having a side surface over an insulating surface will be described with reference to FIGS. As shown in FIG. 5A, a substrate 201 such as a glass substrate is prepared. Over the substrate 201, an insulating film 202 serving as a base of the structure and the semiconductor film is formed. As the insulating film 202, a single layer film or a multilayer film of a silicon oxide film, a silicon nitride film, or a silicon oxynitride film is formed by a plasma CVD method or a sputtering method. The thickness of the insulating film 202 is 50 nm to 200 nm. An island-shaped semiconductor film 204 is formed over the insulating film 202. The thickness of the island-shaped semiconductor film 204 is 10 nm to 40 nm. As the island-shaped semiconductor film 204, an amorphous silicon film, a microcrystalline silicon film, or the like is formed by a plasma CVD method, a low pressure CVD method, a thermal CVD method, or the like. In some cases, such as when silane or the like is used as a source gas, the island-shaped semiconductor film 204 may contain hydrogen depending on a deposition method. In order to prevent hydrogen from being ejected from the island-shaped semiconductor film 204 when the laser beam is irradiated, the island-shaped semiconductor film 204 is dehydrogenated by heating at 400 ° C. to 550 ° C. for about one hour or more.

  By performing a photolithography process and an etching process on the island-shaped semiconductor film 204, the island-shaped semiconductor film 204 having a side surface is formed as illustrated in FIG. In FIG. 6, the island-shaped semiconductor film 204 is provided with a tapered portion so that the cross-sectional shape is trapezoidal. By tilting the side surface of the island-shaped semiconductor film 204, the step coverage of the gate insulating film and the gate wiring formed over the island-shaped semiconductor film 204 can be improved. In the case where the island-shaped semiconductor film 204 is provided with a taper portion, the upper limit of the portion where the laser beam is incident (the width of the island-shaped semiconductor film 204) is set to about 500 nm. This is because the region where the channel is formed only needs to be completely melted.

  A method for forming a structure functioning as a mirror will be described with reference to FIGS. As shown in FIG. 6A, an insulating film 205 is formed. As the insulating film 205, a single layer film or a multilayer film of a silicon oxide film, a silicon nitride film, a silicon oxynitride film is formed by a plasma CVD method or a sputtering method. By performing a photolithography process and an etching process on the insulating film 205, a mask insulating film 206 is formed as shown in FIG. The insulating film 205 is removed so as not to remain in the region where the structure 208 is formed. A metal film that forms the structure 208 needs to be formed over the island-shaped semiconductor film 204, and the mask insulating film 206 is formed in order to avoid contamination of the surface of the island-shaped semiconductor film 204 with this metal film. . Therefore, the mask insulating film 206 is formed so as to completely cover the surface of the island-shaped semiconductor film 204.

  As shown in FIG. 6C, a metal film 207 constituting the structure 208 is formed. The metal film 207 is formed of a metal such as titanium, aluminum, tungsten, or titanium. These metal films can be formed by sputtering. By performing a photolithography process and an etching process on the metal film 207, a structure 208 having a tapered portion is formed as illustrated in FIG. The inclined surface of the taper portion becomes the reflecting surface. In order to provide a taper portion in the metal film, it is preferable to use an ICP (Inductively Coupled Plasma) etching method. Etching conditions (the amount of power applied to a coil-type electrode, the amount of power applied to a substrate-side electrode) The metal film can be etched into a tapered shape by adjusting the amount of electric power and the electrode temperature on the substrate side.

  A method for forming a crystalline semiconductor film will be described with reference to FIGS. After the mask insulating film 206 is removed, a laser beam 209 is irradiated from above the island-like semiconductor film 204 and the structure 208 as shown in FIG. By irradiation while scanning with the laser beam 209, the island-shaped semiconductor film 204 is crystallized as illustrated in FIG. 7B, so that the island-shaped crystalline semiconductor film 210 is formed. The structure 208 is removed, a channel formation region is formed using the island-shaped crystalline semiconductor film 210, and a semiconductor element is formed.

  Note that the laser beam 209 may be irradiated in a state where the island-shaped semiconductor film 204 is covered with the mask insulating film 206 without removing the mask insulating film 206 as shown in FIG. In this case, the mask insulating film 206 is removed after the laser beam 209 is irradiated. In the case where the mask insulating film 206 is an insulating film containing hydrogen, before the laser beam 209 is irradiated, heat treatment is performed at about 400 ° C. to 550 ° C. for about one hour or more, so that the hydrogen of the mask insulating film 206 is increased. I will take out. By irradiating the laser beam 209 with the mask insulating film 206, the island-shaped semiconductor film 204 can be prevented from being contaminated when it is melted.

(Embodiment 4)
In this embodiment, a method for forming a structure body functioning as a mirror and a semiconductor film having a side surface will be described. In Embodiment 3, an example in which the entire structure 208 is formed using a material having high reflectivity such as metal has been described; however, in this embodiment, an insulating film whose surface is covered with a material having high reflectivity is used. A method for forming the structure will be described. This embodiment will be described with reference to FIG. In FIG. 8, the same reference numerals as those in FIGS. 6 to 7 indicate the same components, and redundant descriptions are omitted.

  The island-shaped semiconductor film 204 is formed over the insulating film 202 by the process illustrated in FIGS. An insulating film 211 is formed so as to cover the island-shaped semiconductor film 204. The insulating film 211 is formed of a single layer film or a laminated film of an insulating film selected from silicon oxide, silicon nitride, and silicon oxynitride film. These insulating films can be formed by a plasma CVD method, a sputtering method, or the like. The thickness of the insulating film 211 is the same as or greater than that of the island-shaped semiconductor film 204.

  The insulating film 211 is processed into a predetermined shape by a photolithography process and an etching process, and a structure body 213 having a tapered portion and a mask insulating film 214 covering the island-shaped semiconductor film 204 are formed as shown in FIG. Form.

  As shown in FIG. 8C, a metal film 215 that covers the structure 213 and the mask insulating film 214 is formed by a sputtering method or the like. The metal film 215 is formed of aluminum, titanium, chromium, or the like. The mask insulating film 214 can prevent the island-shaped semiconductor film 204 from being contaminated with the metal film 215.

  The metal film 215 is processed by a photolithography process and an etching process, so that only the metal film 216 covering the surface of the structure 213 is left as illustrated in FIG. As described above, a reflective surface is formed on the inclined surface of the tapered portion of the structure 213.

  As shown in FIG. 8E, the mask insulating film 214 is removed, and the structure 213 covered with the metal film 216 and the island-shaped semiconductor film 204 are irradiated with a laser beam, so that the island-shaped semiconductor film 204 is crystallized. Turn into. Alternatively, laser beam irradiation may be performed in a state covered with the mask insulating film 214 in FIG.

(Embodiment 5)
In this embodiment mode, a method for forming a structure functioning as a prism and a semiconductor film over an insulating surface will be described. This embodiment will be described with reference to FIG. 9 and FIG. 9 and 10, the same reference numerals as those in FIGS. 5 to 7 indicate the same components, and redundant description is omitted.

  The steps described with reference to FIGS. 5A and 5B are performed, so that the insulating film 202 is formed over the substrate 200 and the island-shaped semiconductor film 204 is formed over the insulating film 202. As shown in FIG. 9A, an insulating film 226 is formed over the island-shaped semiconductor film 204. The insulating film 226 is a film constituting the structure. Before the insulating film 226 is formed, the island-shaped semiconductor film is dehydrogenated by heat treatment at 400 ° C. to 550 ° C. for about 1 hour or longer as necessary. After the insulating film 226 is formed, a resist mask 227 is formed over the insulating film 226. The insulating film 226 is etched, so that a structure body 228 having a reverse tapered portion is formed as illustrated in FIG.

As a method for forming a reverse tapered portion in the insulating film 226, in this embodiment mode, the insulating film 226 is formed so that an etching rate of the insulating film 226 becomes higher, and the insulating film 226 is isotropically etched, so that the reverse tapered portion is formed. The example which forms is shown. As the insulating film 226, silane (SiH ₄ ) and dinitrogen monoxide (N ₂ O), or silane (SiH ₄ ), dinitrogen monoxide (N ₂ O), ammonia (NH ₃ ), and hydrogen (H ₂ ) As an example, a case where a silicon oxynitride film is formed by a plasma CVD method and a silicon oxynitride film is etched by hydrofluoric acid will be described. The film formation temperature of the silicon oxynitride film is increased stepwise or continuously. A dense film having a lower etching rate with hydrofluoric acid can be formed as the film forming temperature is higher. In addition, the etching rate by hydrofluoric acid can be reduced as the upper layer is reached by decreasing the flow rate of silane (SiH ₄ ) stepwise or continuously.

  The silicon oxynitride film thus formed is wet etched with hydrofluoric acid. Wet etching is isotropic etching, and the silicon oxynitride film has a lower etching rate with respect to hydrofluoric acid as the upper layer is formed. Therefore, as shown in FIG. 9B, a structure 228 having an inversely tapered portion around is formed. be able to. Note that the insulating film 226 is not limited to a silicon oxynitride film, and may be a silicon oxide film or a silicon nitride film.

  A structure 228 illustrated in FIG. 9B is a structure in which the two structures 31 illustrated in FIG. 4 and a mask insulating film that covers the island-shaped semiconductor film 204 are integrally formed. That is, the structure body 228 has a portion covering the surface of the island-shaped semiconductor film 204 and a portion in contact with the surface of the insulating film 202, and faces the side surface of the island-shaped semiconductor film 204 in a portion in contact with the surface of the insulating film 202. It has a reverse taper part.

  After the structure 228 is formed, the resist mask 227 is removed with a peeling solution. While scanning with the laser beam 209, the laser beam 209 is irradiated from above the island-shaped semiconductor film 204 and the structure 228 as shown in FIG. Before the laser beam 209 is irradiated, hydrogen is extracted from the structure 228 as necessary.

  The laser beam 209 incident on the inversely tapered portion of the structure 228 is reflected at the interface between the reflecting surface (the inclined surface of the inversely tapered portion) and air, and the optical path is deflected. The laser beam 209 reflected by the reflecting surface of the structure 228 propagates through the structure 228 and enters the island-shaped semiconductor film 204 from the side surface. The laser beam 209 incident on the side surface of the island-shaped semiconductor film 204 is totally reflected at the interface between the structure 228 and the island-shaped semiconductor film 204 and at the interface between the insulating film 202 and the island-shaped semiconductor film 204, while in the island-shaped semiconductor film 204. Propagate. As a result, the island-shaped semiconductor film 204 is completely melted, and a crystalline semiconductor film 210 having a large grain crystal is formed. The semiconductor element can be formed by removing the structure body 228 and forming a channel formation region in the island-shaped crystalline semiconductor film 210.

(Embodiment 6)
As described in Embodiment Mode 1, when the laser beam is incident on the semiconductor film from the opposite side surfaces, the width d of the semiconductor film that can be completely melted is about 500 nm. Therefore, the shape of the semiconductor layer (active layer) of a semiconductor element such as a thin film transistor is restricted. In this embodiment, the shape and arrangement of an island-shaped semiconductor film for manufacturing a thin film transistor and a structure body will be described. Note that in this embodiment, the crystallization method of Embodiment 1 is described as an example; however, the crystallization methods described in other embodiments can be similarly performed.

  FIG. 11 is a diagram illustrating a configuration and an arrangement example of an island-shaped semiconductor film and a structure functioning as a mirror. FIG. 11A is a top view, and FIG. 11B is a cross-sectional view taken along A-A ′ in FIG. 11B, an insulating film 402 serving as a base film is formed over a substrate 401. The insulating film 402 is adjacent to the island-shaped semiconductor film 404 and the island-shaped semiconductor film 404 included in the thin film transistor. Thus, two structures 408 functioning as mirrors are formed.

A channel formation region of the thin film transistor is formed in a region 404 a having a narrow central portion of the island-shaped semiconductor film 404. Therefore, as completely melted by laser beam irradiation, the width d ₁ is about 500 nm.

A wide region 404b connected to both sides of the region 404a is a region for forming a high concentration impurity region (a source region or a drain region) of the thin film transistor. The high concentration impurity regions, since the region connecting the source electrode or the drain electrode is required, the width d ₂ wider than 500 nm, to be able to form the contact portion between the source electrode and the drain electrode.

  The high-concentration impurity region does not require as high crystallinity as the channel region. Therefore, in the arrangement example in FIG. 11A, the structure body 408 is formed so as to sandwich the region 404a in the island-shaped semiconductor film 404, and the structure body corresponding to the region 404b is not provided. That is, the structure 408 is formed so that at least the region 404a can be completely melted. In this manner, by forming the structure body 408, the degree of integration of the island-shaped semiconductor film 404 can be increased.

  Irradiation is performed from above the island-shaped semiconductor film 404 and the structure 408 while scanning with a linear laser beam. The region 404a of the island-shaped semiconductor film 404 is completely melted by the structure 408, so that the laser beam is also incident from the side surface, and a large grain crystal is formed. Since there is almost no incidence of the laser beam from the side surface in the region 404b, the crystallization is mostly contributed by the laser beam incident from the upper surface. Therefore, the region 404b is not completely melted by the laser beam, and thus becomes a small grain crystal.

  By irradiation with the laser beam, the island-shaped semiconductor film 404 is crystallized to form an island-shaped crystal semiconductor film. The structure 408 is removed and a thin film transistor is formed using an island-shaped crystalline semiconductor film. With the island-like crystalline semiconductor film, a thin film transistor having a channel formation region with a large grain crystal having a thickness of 40 nm or less can be formed.

  FIG. 12 shows a structural example of a thin film transistor. As shown in FIG. 12, a gate insulating film 412 is formed on the island-like crystalline conductor film 410, and a gate electrode 413 is formed on the gate insulating film 412. An n-type or p-type impurity is added to the island-shaped crystalline semiconductor film 410 to form a high concentration impurity region 410b. As a result, a channel formation region 410 a is determined in the island-shaped crystalline semiconductor film 410. An interlayer insulating film 414 is formed over the gate electrode 413. Contact holes reaching the island-like crystalline semiconductor film 410 are formed in the interlayer insulating film 414 and the gate insulating film 412. An electrode 415 is formed over the interlayer insulating film 414, and the electrode 415 is connected to the high concentration impurity region 410b. Through the above steps, a thin film transistor is manufactured.

Note that as illustrated in FIG. 13, the island-shaped semiconductor film 404 may be interposed between the band-shaped structures 428. In the case of the arrangement example in FIG. 13, the structures 428 are arranged so as to face the two opposite side surfaces of the region 404 b of the island-shaped semiconductor film 404. When the laser beam is irradiated from above the island-shaped semiconductor film 404 and the structure body 428, the structure body 428 causes the laser beam to be incident on the side surface of the region 404b. Accordingly, the width _{d 3} from the side of the region 404b region of about 200nm~300nm is completely melted, a large grain crystal is formed.

In the island-shaped semiconductor film 404 illustrated in FIGS. 11A and 13, since the channel width is determined by the width d ₁ of the region 404 a, the upper limit is limited to 500 nm. FIG. 14 shows an arrangement example of island-shaped semiconductor films and structures for increasing the channel width of the thin film transistor to 500 nm or more. A plurality of regions 434a serving as channel formation regions are provided in the island-shaped semiconductor film 434, and the channel width is set to 500 nm or more. FIG. 14 shows an example in which three regions 434a are formed. Incidentally, in order to completely melt the regions 434a, the width _{d 1} is set to 500nm or less.

  The region 434b to be a high concentration impurity region is formed so as to connect the plurality of regions 434a. In order to completely melt the region 434a, a structure 438 is formed corresponding to the side surface of the composition region 434a. With the arrangement example as shown in FIG. 14, the plurality of regions 434a can be completely melted to form large-grain crystals. On the other hand, the region 434b is a small grain crystal. Therefore, by the crystallization method of the present invention, a thin film transistor having a channel width of 500 nm or more can be formed using a crystalline semiconductor film having a thickness of 40 nm or less and a large crystal grain.

  As described above, a thin film transistor can be manufactured using the island-shaped semiconductor film crystallized by the method of the present invention. Various integrated circuits can be formed using thin film transistors. For example, an active matrix liquid crystal display device or an active matrix EL display device including a thin film transistor in a pixel portion can be manufactured. Further, a semiconductor device capable of wireless communication can be manufactured by manufacturing an integrated circuit having a function of performing wireless communication using a thin film transistor and connecting an antenna to the integrated circuit.

(Embodiment 7)
In this embodiment, an example of a method for manufacturing a nonvolatile memory element which is a semiconductor element will be described with reference to FIGS.

  The nonvolatile memory element described in this embodiment has a structure similar to a MOSFET (Metal Oxide Semiconductor Field Effect Transistor), and a region in which charge can be accumulated for a long period is provided over a channel formation region. This charge storage region is formed on an insulating film and is also called a floating gate electrode because it is isolated from the surroundings. A control gate electrode is provided on the floating gate electrode through an insulating film.

  In the nonvolatile memory element having the above-described structure, an operation for accumulating and releasing charges in the floating gate electrode is performed by a voltage applied to the control gate electrode. In other words, data is stored by taking in and out the electric charge held in the floating gate electrode. In order to inject or withdraw charges from the floating gate electrode, a high voltage is applied between the semiconductor film in which the channel formation region is formed and the control gate electrode. At this time, it is said that Fowler-Nordheim type (FN type) tunnel current (NAND type) and thermal electrons (NOR type) flow through the insulating film on the channel formation region. The insulating film provided over the channel formation region is also called a tunnel insulating film.

  First, as illustrated in FIG. 16A, an insulating film 501 serving as a base film is formed over a substrate 500. An island-shaped crystalline semiconductor film 510 is formed over the insulating film 501 using any of the crystallization methods of Embodiments 1 to 5. The method of Embodiment 6 may be used for the shape of the crystalline semiconductor film 510 and the method for arranging the structure functioning as a mirror or a prism. The thickness of the crystalline semiconductor film 510 is 40 nm or less, preferably 40 nm or less and 10 nm or more.

  As shown in FIG. 16B, a first insulating film 511 is formed over the crystalline semiconductor film 510. The first insulating film 511 can be formed using an insulating material mainly containing silicon such as silicon oxide or silicon oxynitride by a CVD method, a sputtering method, or the like. Alternatively, a material mainly containing a metal oxide such as aluminum oxide (AlxOy), tantalum oxide (TaxOy), or hafnium oxide (HfOx) can be used. The first insulating film 511 is preferably formed with a thickness of 1 nm to 20 nm, preferably 1 nm to 10 nm.

  Next, as shown in FIG. 16C, plasma oxidation is performed on the first insulating film 511 to form a second insulating film 512. A charge storage film 513 is formed over the second insulating film 512. The second insulating film 512 functions as a tunnel insulating film, and the charge storage film 513 functions as a floating gate electrode.

The plasma oxidation performed on the first insulating film 511 is excited at a high frequency such as a microwave (typically 2.45 GHz), has an electron density of 1 × 10 ¹¹ cm ⁻³ or more, and has an electron temperature of plasma. Uses a plasma of 1.5 eV or less. It is preferable to use plasma having an electron density of 1 × 10 ¹¹ cm ^{−3 to} 1 × 10 ¹³ cm ⁻³ and an electron temperature of plasma of 0.5 eV to 1.5 eV. Further, the plasma oxidation time for the first insulating film 511 is preferably 60 seconds or more.

The atmosphere of plasma oxidation is an atmosphere containing at least oxygen (O ₂ ), an atmosphere containing at least dinitrogen monoxide (N ₂ O) and a rare gas, an atmosphere containing at least oxygen, hydrogen (H ₂ ), and a rare gas, or at least An atmosphere containing dinitrogen monoxide, hydrogen, and a rare gas. Note that in the case where the atmosphere contains hydrogen, the proportion is preferably smaller than oxygen, dinitrogen monoxide, and a rare gas.

  As the rare gas, Ar gas or a mixed gas of Ar and Kr is typically used. In the case where the atmosphere of plasma oxidation includes a rare gas, the second insulating film 512 may include a rare gas used for plasma treatment. For example, when Ar is used for plasma oxidation, the second insulating film 512 may contain Ar.

In the plasma oxidation, since the electron density of plasma is as high as 1 × 10 ¹¹ cm ⁻³ or more and the electron temperature in the vicinity of the first insulating film 511 that is an object to be processed is low, the second insulating film 512 is It is possible to prevent damage from plasma. Further, since the electron density of plasma is as high as 1 × 10 ¹¹ cm ⁻³ or higher, a film (here, the second insulating film 511) formed by plasma oxidation of the object to be processed (here, the first insulating film 511). The insulating film 512) can form a dense and high withstand voltage film as compared with a film formed by a CVD method, a sputtering method, or the like. In addition, since the electron temperature of plasma is as low as 1.5 eV or less, the object to be processed can be oxidized at a lower temperature than conventional plasma treatment or thermal oxidation. For example, even if plasma oxidation is performed at a temperature of about 500 ° C. to 600 ° C. lower than the strain point of the glass substrate by 100 ° C. or more, the oxidation treatment can be sufficiently performed.

  By performing plasma oxidation on the insulating film containing hydrogen, a film with a reduced hydrogen content can be obtained.

In this embodiment mode, the first insulating film 511 is subjected to plasma oxidation in an atmosphere of a mixed gas of oxygen (O ₂ ) and argon (Ar). For example, oxygen may be introduced into the plasma oxidation atmosphere in the range of 0.1 to 100 sccm and argon in the range of 100 to 5000 sccm.

  The second insulating film 512 formed by performing plasma oxidation on the first insulating film 511 functions as a tunnel insulating film of the nonvolatile memory element. Accordingly, the thinner the second insulating film 512, the easier the tunnel current flows. In addition, as the second insulating film 512 is thinner, charges can be accumulated in the floating gate electrode formed later at a lower voltage.

  Generally, there is a thermal oxidation method as a method for forming a thin insulating film on a semiconductor film. However, when a substrate having a strain point of less than 700 ° C. such as a glass substrate is used as the substrate 500, the semiconductor film is heated. It is very difficult to form a tunnel insulating film by oxidation. In addition, an insulating film formed by a CVD method or a sputtering method does not have a sufficient withstand voltage because it includes a defect inside the film. Furthermore, when a thin insulating film is formed by a CVD method or a sputtering method, there is a problem that the withstand voltage is low and defects such as pinholes are likely to occur. Therefore, if the first insulating film 511 formed by a CVD method or a sputtering method is used as it is as a tunnel insulating film, defects are likely to occur.

  Therefore, as shown in this embodiment mode, the first insulating film 511 is plasma-oxidized to form the second insulating film 512, which is denser and higher than the insulating film formed by a CVD method, a sputtering method, or the like. A pressure-resistant film can be formed. Further, even when the end portion of the crystalline semiconductor film 510 cannot be sufficiently covered when the first insulating film 511 is formed, the second insulating film 512 that sufficiently covers the semiconductor film is formed by plasma oxidation. be able to.

  The nonvolatile memory element of this embodiment stores information by injecting electrons through a tunnel insulating film. At this time, if hydrogen that causes electron traps exists in the tunnel insulating film, the voltage fluctuates as writing and erasing are repeated, which causes deterioration of the memory. Accordingly, it is preferable that the hydrogen content in the tunnel insulating film, which causes an electron trap, is small. By forming the second insulating film 512 by plasma oxidation of the first insulating film 511, the hydrogen content in the film can be reduced as compared with an insulating film formed by a CVD method, a sputtering method, or the like.

  As described above, the crystalline semiconductor film 510 in which the channel formation region is formed is formed as thin as 40 nm or less, and the tunnel insulating film is oxidized by oxygen plasma oxidation having a high electron density. Possible non-volatile memory elements can be formed.

  The charge storage film 513 can be formed of a single layer film or a stacked film of two or more layers. For example, the charge storage film 513 includes a semiconductor material such as silicon (Si) and germanium (Ge), a compound containing silicon as a main component, tungsten (W), titanium (Ti), tantalum (Ta), and molybdenum. It is formed using a material selected from a metal selected from (Mo) or the like, an alloy containing these metals as main components, and a metal compound (metal nitride, metal oxide, etc.) containing these metals as main components. Can do.

  For example, as a compound containing silicon as a main component, there are silicon nitride, silicon nitride oxide, silicon carbide, silicide (tungsten silicide, titanium silicide, nickel silicide), and the like. Examples of the semiconductor material include n-type or p-type silicon and silicon germanium containing germanium at a concentration of less than 10 atomic%. Examples of the metal compound include tantalum nitride, tantalum oxide, tungsten nitride, titanium nitride, titanium oxide, and tin oxide. In the case of using silicon, an impurity imparting conductivity such as phosphorus or boron may be added.

  As shown in FIG. 16D, a third insulating film 514 is formed over the charge storage film 513. The thickness of the third insulating film 514 is 1 nm to 100 nm, and preferably 20 nm to 60 nm. The third insulating film 514 is made of an insulating material mainly containing silicon such as silicon oxide or silicon oxynitride, or a metal oxide such as aluminum oxide (AlxOy), tantalum oxide (TaxOy), or hafnium oxide (HfOx). Form. These membranes. It is formed using a CVD method or a sputtering method.

  Plasma oxidation is performed on the third insulating film 514 in the same manner as the oxidation plasma treatment of the first insulating film 511. As shown in FIG. 17A, the fourth insulating film 515 is formed by performing plasma oxidation on the third insulating film 514. Next, a conductive film 516 and a conductive film 517 are sequentially stacked over the fourth insulating film 515.

  The conductive films 516 and 517 are conductive films constituting a gate electrode (control gate electrode). Although an example in which the gate electrode is formed using a two-layer conductive film has been described, a single layer or three or more layers may be used. The conductive film constituting the control gate electrode is n-type or p-type silicon, tantalum (Ta), tungsten (W), titanium (Ti), molybdenum (Mo), aluminum (Al), copper (Cu), chromium ( Cr), niobium (Nb), etc., an alloy containing these metals as the main component, and a metal compound (metal nitride, metal oxide, etc.) containing these metals as the main component. Can do.

  A resist mask is formed by a photolithography process. The conductive films 516 and 914 are etched using this resist mask, so that a gate electrode 520 is formed over the crystalline semiconductor film 510 as illustrated in FIG. Further, the fourth insulating film 515 and the charge storage film 513 are etched using the gate electrode 520 as a mask. As a result, the gate electrode 520, the fourth insulating film 515, and the charge storage film 513 are formed so that the side surfaces thereof are substantially coincident with each other. The charge storage film 513 functions as a floating gate electrode, the fourth insulating film 515 functions as a control insulating film, and the gate electrode 520 functions as a control gate electrode.

  As shown in FIG. 17C, an impurity imparting n-type or p-type is added using the gate electrode 520 as a mask, and a pair of impurity regions 522 and a channel formation region 523 located between the pair of impurity regions 522 are added. Form. Phosphorous (P), arsenic (As), or the like can be used as an impurity imparting n-type, and boron (B) or the like can be used as an impurity exhibiting p-type. After adding an impurity imparting n-type or p-type, heat treatment for activating this impurity is performed.

  As shown in FIG. 17D, a sixth insulating film 524 is formed so as to cover the gate electrode 520. An opening reaching the impurity region 522 is formed in the sixth insulating film 524 and the second insulating film 512. An electrode 525 connected to the impurity region 522 is formed over the sixth insulating film 524.

  Through the above process, a nonvolatile memory element which is a semiconductor element can be manufactured. Note that the structure of the nonvolatile memory element described in this embodiment mode is an example, and the semiconductor film crystallized by the method of the present invention in the nonvolatile memory element of another structure and described in this embodiment mode. Needless to say, an insulating film formed by plasma treatment can be applied.

  In this embodiment, a method for manufacturing a semiconductor device using a semiconductor film crystallized by the method of the present invention will be described. A structure and a manufacturing method of a semiconductor device in which data is input and output wirelessly as an example will be described.

  In recent years, wireless chips have been spotlighted as small semiconductor devices that combine an ultra-small IC chip and an antenna for wireless communication. The wireless chip can write and read data by transmitting and receiving a communication signal (operation magnetic field) using a wireless communication device (hereinafter referred to as a reader / writer).

  As an application field of the wireless chip, for example, merchandise management in the distribution industry can be cited. At present, merchandise management using bar codes and the like is the mainstream, but since bar codes are optically read, data cannot be read if there is a shield. On the other hand, since the wireless chip reads data wirelessly, it can be read even if there is a shielding object. Accordingly, it is possible to realize efficient merchandise management and cost reduction. In addition, it can be used in a wide range of applications such as boarding tickets, air passenger tickets, and automatic payment of fare.

  As the application field of wireless chips is expanding, the demand for higher-performance wireless chips is also increasing. For example, it is possible to prevent data leakage to a third party by encrypting transmission / reception data. For this, a method of processing the decryption and encryption processing in hardware, a method of processing in software, and a method of using both hardware and software are conceivable. In the method of processing in hardware, an arithmetic circuit is configured by a dedicated circuit that performs decryption or encryption. In the method of processing in software, an arithmetic circuit is configured by a CPU (Central Processing Unit) and a large-scale memory, and a decryption program and an encryption program are executed by the CPU. In the method using both hardware and software, a dedicated circuit, CPU, and memory constitute an arithmetic circuit, and the dedicated circuit performs a part of the arithmetic processing for decryption and encryption, and the rest of the arithmetic processing is performed. Run the program on the CPU. In any case, it is required to mount a large-capacity memory on the wireless chip.

  In this embodiment, a wireless chip having an encryption processing function will be described as an example of a semiconductor device including a CPU, a dedicated circuit, and a memory circuit. FIG. 18 illustrates an example of a block diagram of a semiconductor device.

The semiconductor device 2601 includes an arithmetic circuit 2606 and an analog unit 2615. The arithmetic circuit 2606 includes a CPU 2602, a ROM 2603, a RAM 2604, and a controller 2605. The analog portion 2615 includes an antenna 2607, a resonance circuit 2608, a power supply circuit 2609, a reset circuit 2610, a clock generation circuit 2611, a demodulation circuit 2612, a modulation circuit 2613, and a power management circuit 2614.

  The ROM 2603 can be composed of a memory circuit having the nonvolatile memory element of Embodiment 7 in a memory cell and a mask ROM using a thin film transistor. As the RAM 2604, a DRAM or SRAM using a thin film transistor can be used. By applying the present invention, both the ROM 2603 and the RAM 2604 can reduce power consumption. In addition, heat generation of the semiconductor device 2601 can be reduced by reducing power consumption.

  The controller 2605 includes a CPU interface (CPUIF) 2616, a control register 2617, a code extraction circuit 2618, and an encoding circuit 2619. Note that in FIG. 18, for simplification of description, the communication signal is illustrated as being divided into a reception signal 2620 and a transmission signal 2621, but in reality, both are integrated signals, and the semiconductor device 2601. Are simultaneously transmitted and received between the reader / writer. Received signal 2620 is received by antenna 2607 and resonant circuit 2608, and then demodulated by demodulation circuit 2612. The transmission signal 2621 is modulated by the modulation circuit 2613 and then transmitted from the antenna 2607.

  In FIG. 18, when the semiconductor device 2601 is placed in a magnetic field formed by a communication signal, an induced electromotive force is generated by the antenna 2607 and the resonance circuit 2608. The induced electromotive force is held by the electric capacity in the power supply circuit 2609 and the potential thereof is stabilized, and the induced electromotive force is supplied to each circuit of the semiconductor device 2601 as a power supply voltage. The reset circuit 2610 generates an initial reset signal for the entire semiconductor device 2601. For example, a signal that rises after a rise in the power supply voltage is generated as a reset signal. The clock generation circuit 2611 changes the frequency and duty ratio of the clock signal in accordance with the control signal generated by the power management circuit 2614. The demodulation circuit 2612 detects the fluctuation of the amplitude of the ASK reception signal 2620 as “0” / “1” reception data 2622. The demodulation circuit 2612 is a low-pass filter, for example. Further, the modulation circuit 2613 transmits the transmission data by changing the amplitude of the ASK transmission signal 2621. For example, when the transmission data 2623 is “0”, the resonance point of the resonance circuit 2608 is changed, and the amplitude of the communication signal is changed. The power management circuit 2614 monitors the power supply voltage supplied from the power supply circuit 2609 to the arithmetic circuit 2606 or the current consumption in the arithmetic circuit 2606, and a control signal for changing the frequency and duty ratio of the clock signal in the clock generation circuit 2611. Is generated.

  An operation of the semiconductor device 2601 in FIG. 18 will be described. First, the semiconductor device 2601 receives a reception signal 2620 including ciphertext data based on a reception signal 2620 transmitted from the reader / writer. The received signal 2620 is demodulated by the demodulation circuit 2612, decomposed into a control command, ciphertext data, and the like by the code extraction circuit 2618 and stored in the control register 2617. Here, the control command is data specifying a response of the semiconductor device 2601. For example, transmission of a unique ID number, operation stop, and decryption are designated. Here, it is assumed that a decryption control command is received.

  Subsequently, in the arithmetic circuit 2606, the CPU 2602 decrypts (decrypts) the ciphertext using the secret key 2624 stored in advance in the ROM 2603 according to the decryption program stored in the ROM 2603. The decrypted ciphertext (decrypted text) is stored in the control register 2617. At this time, the RAM 2604 is used as a data storage area. The CPU 2602 accesses the ROM 2603, the RAM 2604, and the control register 2617 via the CPUIF 2616. The CPUIF 2616 has a function of generating an access signal for any of the ROM 2603, the RAM 2604, and the control register 2617 from the address requested by the CPU 2602.

  Finally, in the encoding circuit 2619, transmission data 2623 is generated from the decoded text, modulated by the modulation circuit 2613, and the transmission signal 2621 is transmitted from the antenna 2607 to the reader / writer.

  Note that the semiconductor device 2601 in FIG. 18 employs a software processing method as an arithmetic method, but the semiconductor device 2601 may be configured by selecting an optimal arithmetic method according to the purpose. The method of processing in software is a method in which a CPU and a large-scale memory constitute an arithmetic circuit and a program is executed by the CPU. Other calculation methods include a method for processing operations in hardware and a method using both hardware and software. In the method of processing in hardware, an arithmetic circuit may be configured with a dedicated circuit. In the method using both hardware and software, an arithmetic circuit is configured by a dedicated circuit, a CPU, and a memory, a part of the arithmetic processing is performed by the dedicated circuit, and the remaining arithmetic processing program is executed by the CPU.

  Next, a method for manufacturing the semiconductor device 2601 is described. In this embodiment, a circuit constituting a semiconductor device is formed with a thin film transistor or a nonvolatile memory element, and the circuit is transferred from a substrate used for manufacturing the thin film transistor to a flexible substrate to manufacture a flexible semiconductor device. How to do.

  In order to describe a manufacturing method of the semiconductor device 2601, as a semiconductor element included in the semiconductor device 2601, a p-channel TFT (also referred to as “pch-TFT”) and an n-channel TFT (“Nch−”) that form an inverter or the like are used. “TFT”)), a high voltage n-channel TFT used for a capacitor, a power supply circuit, and the like is typically shown. Hereinafter, a method for manufacturing a wireless chip will be described with reference to cross-sectional views illustrated in FIGS.

A glass substrate is used as the substrate 260. As shown in FIG. 19A, a separation layer 261 including three layers 261a to 261c is formed over a substrate 260. For the first layer 261a, a silicon oxynitride film (SiO _x Ny, x>y> 0) is formed to a thickness of 100 nm using SiH ₄ and N ₂ O as a source gas by a parallel plate plasma CVD apparatus. As the second layer 261b, a tungsten film with a thickness of 30 nm is formed with a sputtering apparatus. As the third layer 261c, a silicon oxide film with a thickness of 200 nm is formed with a sputtering apparatus.

  By forming the third layer 261c (silicon oxide), the surface of the second layer 261b (tungsten) is oxidized, and tungsten oxide is formed at the interface. By forming the tungsten oxide, the substrate 260 can be easily separated when the semiconductor element is transferred to another substrate later. The first layer 261a is a layer for maintaining the adhesion of the second layer 261b while manufacturing the semiconductor element.

  The second layer 261b includes tungsten (W), molybdenum (MO), titanium (Ti), tantalum (Ta), niobium (Nb), nickel (Ni), cobalt (CO), zirconium (Zr), zinc ( ZN), ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium (Os), iridium (Ir) metal films, and compounds of these metals are preferred. The thickness of the second layer 261b is 20 nm or more and 40 nm or less.

As shown in FIG. 19B, a base insulating layer 249 having a two-layer structure is formed over the separation layer 261. As the first layer 249a, silicon oxynitride (SiO _x N _y , x <y) is formed to a thickness of 50 nm using SiH ₄ , N ₂ O, NH ₃ , and H ₂ as a source gas by a plasma CVD apparatus. The barrier property is improved so that the nitrogen composition ratio of the first layer 249a is 40% or more. For the second layer 249b, silicon oxynitride (SiO _x N _y , x>y> 0) is formed to a thickness of 100 nm using SiH ₄ and N ₂ O as a source gas by a plasma CVD apparatus. The composition ratio of nitrogen in the second layer 249b is 0.5% or less.

Over the base insulating layer 249, an amorphous silicon film having a thickness of 40 nm or less is formed using SiH ₄ and H ₂ as a source gas by a plasma CVD apparatus. An amorphous silicon film is formed into an island shape by etching, and the island-shaped amorphous silicon film is crystallized by the method described in Embodiment Modes 1 to 4, and as shown in FIG. The crystalline semiconductor films 273 to 276 are formed. In the island-like crystalline semiconductor films 273 to 275, a channel formation region, a source region, and a drain region of the TFT are formed, respectively. The island-like crystalline semiconductor film 276 constitutes an electrode of the MIS type capacitor.

As shown in FIG. 20A, a resist R31 is formed by a photolithography process, and a small amount of p-type impurity is added to the island-like crystalline semiconductor films 274 and 275 of the n-channel TFT. Here, diborane (B ₂ H ₆ ) diluted with hydrogen is used as a doping gas, and boron is doped into the island-shaped crystalline semiconductor films 274 and 275 with an ion doping apparatus. When the doping is completed, the resist R31 is removed.

The purpose of the process of FIG. 20A is to prevent the threshold voltage of the n-channel TFT from becoming a negative voltage. Boron may be added to the island-shaped crystalline semiconductor films 274 and 275 of the n-channel TFT at a concentration of 5 × 10 ¹⁵ atoms / cm ^{3 to} 1 × 10 ¹⁷ atoms / cm ³ . The process in FIG. 20A is performed as necessary.

As shown in FIG. 20B, an insulating film 277 is formed over the entire substrate 260. The insulating film 277 becomes a gate insulating film of the TFT and a dielectric of the capacitor. Here, a silicon oxynitride film (SiO _x N _y , x>y> 0) is formed to a thickness of 20 nm to 40 nm by the plasma CVD apparatus using the source gases SiH ₄ and N ₂ O by the plasma CVD apparatus.

As shown in FIG. 20C, a resist R32 is formed by a photolithography process, and an n-type impurity is added to the island-shaped crystalline semiconductor film 276 of the capacitor. Using phosphine (PH ₃ ) diluted with hydrogen as a doping gas, the island-shaped crystalline semiconductor film 276 is doped with phosphorus by an ion doping apparatus, and an n-type impurity region 279 is formed in the entire island-shaped crystalline semiconductor film 276. . When the doping process is completed, the resist R32 is removed.

  As shown in FIG. 20D, a conductive film 281 is formed over the insulating film 277. The conductive film 281 forms a gate electrode of the TFT. Here, the conductive film 281 has a two-layer structure. The first layer is tantalum nitride (TaN) with a thickness of 30 nm, and the second layer is tungsten (W) with a thickness of 370 nm. Tantalum nitride and tungsten are each formed with a sputtering apparatus.

  A resist is formed over the conductive film 281 by a photolithography process, and the conductive film 281 is etched by an etching apparatus, so that the first conductive films 284 to 286 are formed into island-like crystalline semiconductor films 273 as illustrated in FIG. Form on ~ 276. The first conductive films 283 to 285 serve as TFT gate electrodes or gate wirings. In the high breakdown voltage n-channel TFT, the conductive film 285 is formed so that the gate width (channel length) is wider than that of other TFTs. The first conductive film 286 forms one electrode of the capacitor.

The conductive film 281 is etched by a dry etching method. An ICP (Inductively Coupled Plasma) etching apparatus is used as the etching apparatus. As an etchant, first, a mixed gas of Cl ₂ , SF ₆ , and O ₂ is used to etch tungsten. Next, the etchant introduced into the processing chamber is changed to only Cl ₂ gas, and tantalum nitride is etched. .

As shown in FIG. 21B, a resist R33 is formed by a photolithography process. An n-type impurity is added to the island-like crystalline semiconductor films 274 and 275 of the n-channel TFT. Using the first conductive film 284 as a mask, n-type low-concentration impurity regions 288 and 289 are formed in the island-like crystalline semiconductor film 274 in a self-aligning manner. Further, the n-type low concentration impurity regions 290 and 291 are formed in the island-like crystalline semiconductor film 275 in a self-aligning manner using the first conductive film 285 as a mask. Phosphine (PH ₃ ) diluted with hydrogen is used as a doping gas, and phosphorus is added to the island-shaped crystalline semiconductor films 274 and 275 by an ion doping apparatus. The process of FIG. 21B is a process for forming an LDD region in an n-channel TFT. The n-type impurities in the n-type low-concentration impurity regions 288 and 289 are included in the range of 1 × 10 ¹⁶ atoms / cm ^{3 to} 5 × 10 ¹⁸ atoms / cm ³ .

As shown in FIG. 21C, a resist R34 is formed by a photolithography process, and a p-type impurity is added to the island-shaped crystalline semiconductor film 273 of the p-channel TFT. In the island-like crystalline semiconductor film 272, the portion to be left as the n-type impurity region is covered with the resist R34, so that the exposed region becomes the p-type impurity region. Using the first conductive film 283 as a mask, p-type high-concentration impurity regions 273a and 273b are formed in the island-like crystalline semiconductor film 273 in a self-aligning manner. A region 273c covered with the first conductive film 283 is formed in a self-aligned manner as a channel formation region. For the addition of the p-type impurity region, diborane (B ₂ H ₆ ) diluted with hydrogen is used as a doping gas. When the doping is completed, the resist R34 is removed.

As shown in FIG. 21D, insulating layers 293 to 296 are formed around the first conductive films 283 to 286. The insulating layers 293 to 296 are called sidewalls and side walls. First, a silicon oxynitride film (SiO _x N _y , x>y> 0) is formed to a thickness of 100 nm by a plasma CVD apparatus using SiH ₄ and N ₂ O as source gases. Next, a silicon oxide film is formed to a thickness of 200 nm by an LPCVD apparatus using SiH ₄ and N ₂ O as source gases. A resist is formed by a photolithography process. Using this resist, first, an upper silicon oxide film is wet-etched with buffered hydrofluoric acid. Next, the insulating layers 293 to 296 are formed by removing the resist and subjecting the lower silicon nitride oxide film to dry etching. In this series of steps, the insulating film 277 made of silicon oxynitride is also etched, and the insulating film 277 remains only below the first conductive films 283 to 285 and the insulating layers 293 to 296.

  As shown in FIG. 22A, a resist R35 is formed by a photolithography process. An n-type impurity is added to the island-like crystalline semiconductor films 274 and 275 of the n-channel TFT and the semiconductor layer of the capacitor to form an n-type high concentration impurity region. In the island-like crystalline semiconductor film 274, the first conductive film 284 and the insulating layer 294 are used as masks, and n-type impurities are further added to the n-type low concentration impurity regions 288 and 299. As a result, n-type high concentration impurity regions 274a and 274b are formed in a self-aligned manner. A region 274c overlapping with the first conductive film 284 is determined as a channel formation region in a self-aligning manner. In addition, regions 274e and 274d overlapping with the insulating layer 294 in the n-type low concentration impurity regions 288 and 299 are determined as n-type low concentration impurity regions. Similarly to the island-like crystalline semiconductor film 274, the island-like crystalline semiconductor film 275 is formed with n-type high concentration impurity regions 275a and 275b, a channel formation region 275c, and n-type low concentration impurity regions 275e and 275d. The first conductive film 286 and the insulating layer 296 serve as a mask, and n-type impurities are further added to the n-type impurity region 279, so that n-type high-concentration impurity regions 276a and 276b are formed in a self-aligned manner. A region of the island-shaped crystalline semiconductor film 276 that overlaps with the first conductive film 286 and the insulating layer 296 is determined as an n-type impurity region 276c.

As described above, the n-type impurity addition step uses an ion doping apparatus and phosphine (PH ₃ ) diluted with hydrogen as a doping gas. Phosphorus is present in the n-type high-concentration impurity regions 274a, 274b, 275a, and 275b of the n-channel TFT so that the phosphorus concentration is in the range of 1 × 10 ²⁰ atoms / cm ^{3 to} 2 × 10 ²¹ atoms / cm ^3. Doped.

The resist R35 is removed, and a cap insulating film 298 is formed as shown in FIG. As the cap insulating film 298, a silicon oxynitride film (SiO _x N _y , x>y> 0) is formed to a thickness of 50 nm by a plasma CVD apparatus. SiH ₄ and N ₂ O are used as a source gas for the silicon oxynitride film. After the cap insulating film 298 is formed, heat treatment is performed at 550 ° C. in a nitrogen atmosphere, and the n-type impurity and the p-type impurity added to the island-like crystalline semiconductor films 273 to 276 are activated.

As shown in FIG. 22C, a first interlayer insulating film 300 is formed. The first interlayer insulating film 300 has a two-layer structure. As the first insulating film, silicon oxynitride (SiO _x N _y , 0 <x <y) is formed to a thickness of 100 nm using SiH ₄ and N ₂ O as a source gas by a plasma CVD apparatus. The second insulating film is made of silicon oxynitride (SiO _x N _y , x>y> 0) with a thickness of 600 nm using SiH ₄ , N ₂ O, NH ₃ , H ₂ as a source gas by a plasma CVD apparatus. Form to thickness.

  The first interlayer insulating film 300 and the cap insulating film 298 are removed by a photolithography process and a dry etching process, and a contact hole is formed. A conductive film is formed on the first interlayer insulating film 300. Here, the conductive film has a four-layer structure. From the bottom, 60 nm thick Ti, 40 nm TiN, 500 nm pure aluminum, and 100 nm TiN are stacked in this order. Each layer is formed by a sputtering apparatus. The conductive film is processed into a predetermined shape by a photolithography process and a dry etching process, and second conductive films 303 to 314 are formed.

  Note that in order to explain that the second conductive film 312 and the first conductive film 286 are connected, the drawing shows the second conductive film 312 and the first conductive film 286 connected on the semiconductor layer. Actually, the contact portion between the second conductive film 312 and the first conductive film is formed so as to avoid the semiconductor layer.

  The n-type high-concentration impurity regions 276a and 276b are connected by the second conductive film 312, and a MIS type capacitor having a stacked structure including the n-type impurity region 276c, the insulating film 277, and the first conductive film 286 is formed. The second conductive film 314 is a terminal of the antenna circuit and is connected to the antenna 322.

  As shown in FIG. 23A, a second interlayer insulating film 316 is formed. A contact hole reaching the second conductive film 314 is formed in the second interlayer insulating film 316. An example in which the second interlayer insulating film 316 is formed of photosensitive polyimide is shown. Polyimide is applied with a thickness of 1.5 μm using a spinner. Using a photolithography process, the polyimide is exposed and developed to form a polyimide having contact holes. After development, the polyimide is baked.

  Further, a conductive film is formed over the second interlayer insulating film 316. The conductive film is processed into a predetermined shape by a photolithography process and an etching process, and a third conductive film 320 is formed. As a conductive film constituting the third conductive film 320, Ti with a thickness of 100 nm is formed with a sputtering apparatus. The third conductive film 320 is an antenna bump for connecting the antenna 322 to a terminal of the antenna circuit (second conductive film 314).

  As shown in FIG. 23B, a third interlayer insulating film 321 in which an opening is formed is formed. Here, it is formed of photosensitive polyimide in the same manner as the second interlayer insulating film 316. The opening is formed in a region where the antenna 322 is formed.

  As shown in FIG. 23B, an antenna 322 is formed. Aluminum is vapor-deposited by a vapor deposition apparatus using a metal mask, and an antenna 322 having a predetermined shape is formed in the opening.

  Through the steps shown in FIGS. 20A to 23B, a semiconductor device having a wireless communication function is formed over the substrate 260. Next, as shown in FIG. 24, a process of sealing the semiconductor device in a flexible substrate will be described.

  A protective insulating layer 323 for protecting the antenna 322 is formed. By performing a photolithography process and an etching process or irradiating laser light, the insulating film stacked over the substrate 260 together with the protective insulating layer 323 is removed, and an opening reaching the peeling layer 261 is formed. A large number of integrated circuits constituting a semiconductor device are formed over the substrate 260. In order to peel all the integrated circuits on the substrate 260 together from the substrate 260, an opening is formed so as to surround all the integrated circuits.

  Next, after the substrate for transfer is temporarily fixed on the upper surface of the protective insulating layer 323, the substrate 260 is peeled off. Since the bonding is weak at the interface between the second layer 261b and the third layer 261c of the separation layer 261, the separation progresses from the end of the opening by applying physical force, and the substrate 260 is separated from the semiconductor element. be able to. The flexible substrate 324 is fixed to the base insulating layer 249 from which the substrate 260 has been peeled off with an adhesive. Then, the substrate for transfer is removed. Since a large number of integrated circuits are fixed to the flexible substrate 324, the flexible substrate 324 is divided for each integrated circuit by irradiation with laser light. The other flexible substrate 325 is fixed to the protective insulating layer 253 with an adhesive. Then, the integrated circuit and the antenna are sealed by the flexible substrate 324 and the flexible substrate 325 by performing heat treatment while applying pressure from the outside of the flexible substrate 324 and the flexible substrate 325.

  In this embodiment, the example in which the antenna 322 is formed with the semiconductor element has been described, but an external antenna can also be used. Further, although an example in which the substrate 260 used at the time of manufacturing is peeled is shown in this embodiment, the substrate used at the time of manufacturing can be left. In this case, the substrate may be polished or ground so that the substrate is bent.

  A method for using a semiconductor device capable of wireless communication will be described with reference to FIG.

  There are a wide range of uses for semiconductor devices capable of wireless communication. For example, banknotes, coins, securities, bearer bonds, certificates (driver's license, resident's card, etc., see FIG. 25A), packaging containers (Wrapping paper, bottles, etc., see FIG. 25C), recording media (DVD software, video tape, etc., see FIG. 25B), vehicles (bicycles, etc., see FIG. 25D), personal items ( Such as bags, glasses, etc.), foods, plants, animals, human bodies, clothing, daily necessities, electronic products, etc., and goods such as luggage tags (see FIGS. 25E and 25F) It can be provided and used.

  The semiconductor device 2601 is fixed to an article by being mounted on a printed board, pasted on a surface, or embedded. For example, a book is embedded in paper, and a package made of an organic resin is embedded in the organic resin and fixed to each article. Since the semiconductor device 2601 is small, thin, and lightweight, it does not impair the design of the article itself even after being fixed to the article. In addition, an authentication function can be provided by providing the semiconductor device 2601 in bills, coins, securities, bearer bonds, certificates, and the like, and forgery can be prevented by using this authentication function. Further, by attaching the semiconductor device of the present invention to packaging containers, recording media, personal items, foods, clothing, daily necessities, electronic devices, etc., the efficiency of a system such as an inspection system can be improved.

  A configuration example of an active matrix liquid crystal module as a semiconductor device of the present invention will be described with reference to FIG. 26A is a front view of the liquid crystal module, and FIG. 26B is a cross-sectional view taken along line A-A ′ in FIG.

  Reference numeral 1200 denotes a first substrate, 1201 indicated by a dotted line denotes a driver circuit portion (source side driver circuit), 1202 denotes a pixel portion, and 1203 denotes a driver circuit portion (gate side driver circuit). Over the first substrate 1200, a pixel portion 1202, a source side driver circuit portion 1201, and a gate side driver circuit 1203 made of a thin film transistor or the like are formed. By using a crystalline semiconductor film crystallized by the method of the present invention for a thin film transistor, a liquid crystal module capable of high performance and low voltage driving can be manufactured.

  Next, a cross-sectional structure of the liquid crystal module will be described with reference to FIG. The semiconductor element is formed on a base film 1209 made of an insulating film. The source side driver circuit 1201 includes a CMOS circuit in which an n-channel thin film transistor 1211 and a p-channel thin film transistor 1212 are combined. The pixel portion 1202 includes a switching thin film transistor 1213 and a capacitor 1214. The switching thin film transistor 1213 is covered with an interlayer insulating film 1221. A pixel electrode 1222 is formed on the interlayer insulating film 1221. The pixel electrode 1222 is electrically connected to the switching thin film transistor 1213.

  A protective film 1223 is formed so as to cover the wiring of the switching thin film transistor 1213, the pixel electrode 1222, the n-channel thin film transistor 1211, and the p-channel thin film transistor 1212. The protective film 1223 can prevent impurities from entering the active layer of the thin film transistor, the interlayer insulating film 1221, and the like. An alignment film 1224 is formed over the protective film 1223. The alignment film 1224 is formed as necessary.

  A wiring 1210 is a wiring for transmitting a signal input to the source side driver circuit 1201 and the gate side driver circuit 1203, and is connected to an FPC (flexible printed circuit) 1208 serving as an external input terminal. The liquid crystal module includes a form in which only the FPC 1208 is attached and a form in which both the FPC 1208 and the PWB are attached.

  A liquid crystal module in FIG. 26 includes a liquid crystal module substrate having a first substrate 1200 and a semiconductor element, a counter substrate having a second substrate 1230 as a base material, a sealant 1205, a liquid crystal 1240, and an FPC (flexible flexible substrate). Printed circuit) 1208 and can be bent.

  As the counter substrate, a color filter 1231, a black matrix (BM) 1232, a counter electrode 1233, and an alignment film 1234 are formed over a second substrate 1230. The color filter 1231 can also be provided on the first substrate 1200 side. Further, an IPS liquid crystal module can be formed by providing the counter electrode 1233 in the pixel portion 1202.

  The second substrate 1230 is fixed by a sealant 1205 so as to face the first substrate 1200, and the liquid crystal 240 is sealed between the first substrate 1200 and the first substrate 1204 by the sealant 1205. .

  In FIG. 26, the example in which the driver circuit portions 1201 and 1203 are formed over the first substrate 1200 together with the pixel portion 1202 is shown; however, only the pixel portion 1202 is formed using the crystalline silicon film of the present invention. The driver circuits 1201 and 1203 formed above are formed using an IC chip using a silicon wafer and are electrically connected to the pixel portion 1202 over the first substrate 1200 by a COG method or a TAB method. You can also.

  A configuration example of an active matrix EL (electroluminescence) module will be described as a semiconductor device of the present invention with reference to FIG. FIG. 27A is a front view of the EL module, and FIG. 27B is a cross-sectional view taken along A-A ′ in FIG.

  The EL module illustrated in FIG. 27 has a structure in which a semiconductor element and a light-emitting element are sealed with a first substrate 301, a second substrate 1306, and a sealant 1305. A pixel portion 1302, a signal line driver circuit 1303, and a scanning line driver circuit 1304 are formed over the first substrate 1301, and an EL module substrate is formed. By using a crystalline semiconductor film crystallized by the method of the present invention for a thin film transistor, an EL module capable of high performance and low voltage driving can be manufactured.

  The EL module is formed by sealing the EL module substrate with the sealant 1305 and the first substrate 1306. A space sealed by the EL module substrate, the sealing material 1305, and the second substrate 1306 is filled with a filler 1307. As the filler 1307, an ultraviolet curable resin or a thermosetting resin can be used in addition to an inert gas such as nitrogen or argon.

  The pixel portion 1302, the signal line driver circuit 1303, and the scan line driver circuit 1304 each include a plurality of thin film transistors. FIG. 27B illustrates a thin film transistor 1308 included in the signal line driver circuit 1303 and a thin film transistor 1310 included in the pixel portion 1302. Only illustrated. The pixel portion 1302 includes a light-emitting element 1311, and the light-emitting element 1311 is electrically connected to the thin film transistor 1310.

  The lead wiring 1314 is a wiring for supplying a signal and power from the outside of the EL module. The lead wiring 1314 is connected to the connection terminal 1316 having a two-layer structure through the lead wiring 1315b and the lead wiring 1315a. The connection terminal 1316 is electrically connected to a terminal of a flexible printed circuit (FPC) 1318 by an anisotropic conductive film 1319.

  The semiconductor device of the present invention includes an electronic device including the liquid crystal module described in Embodiment 3 or the EL module of Embodiment 4 in a display portion. Hereinafter, the liquid crystal module and the EL module are collectively referred to as a “display module”. Such electronic devices include computer monitors, television devices (also simply referred to as televisions or television receivers), digital cameras, digital video cameras, mobile phone devices (also simply referred to as mobile phones and mobile phones), and PDAs. (Personal Digital Assistant) and other portable information terminals, notebook computers, car audio systems, navigation systems, digital music players, portable DVD players, portable game machines, and arcade game machines. A specific example of the electronic device will be described with reference to FIG.

  A portable information terminal shown in FIG. 28A includes a main body 9201, a display portion 9202, and the like. By applying the module described in Embodiment 3 or 4 to the display portion 9202, a high-definition display and a low power consumption band information terminal can be provided.

  A digital video camera shown in FIG. 28B includes a display portion 9701, a display portion 9702, and the like. By applying the module described in Embodiment 3 or 4 to the display portion 9701, a digital video camera with high-definition display and low power consumption can be provided.

  A portable terminal illustrated in FIG. 28C includes a main body 9101, a display portion 9102, and the like. By applying the module described in Embodiment 3 or 4 to the display portion 9102, a portable terminal with high-definition display and low power consumption can be provided.

  A portable television device illustrated in FIG. 28D includes a main body 9301, a display portion 9302, and the like. By applying the module described in Embodiment 3 or 4 to the display portion 9302, a portable television device with high definition display and low power consumption can be provided. Such a television device can be widely applied from a small one mounted on a portable terminal such as a cellular phone to a medium-sized one that can be carried and a large one (for example, 40 inches or more). .

  A portable computer shown in FIG. 28E includes a main body 9401, a display portion 9402, and the like. By applying the module described in Embodiment 3 or 4 to the display portion 9402, a portable computer with high image quality and low power consumption can be provided.

  A television device illustrated in FIG. 28F includes a main body 9501, a display portion 9502, and the like. By applying the module described in Embodiment 3 or 4 to the display portion 9502, a high-definition display and a low power consumption television device can be provided.

It is sectional drawing explaining the crystallization method using the structure which functions as a mirror. FIG. 3 is a sectional view taken along line x-x ′ of FIG. 2. It is a top view explaining the crystallization method using the structure which functions as a mirror. It is sectional drawing explaining the crystallization method using the structure which functions as a mirror. It is sectional drawing explaining the crystallization method using the structure which functions as a prism. It is sectional drawing explaining the method of forming the semiconductor film which has a side surface on an insulating surface. FIG. 10 is a cross-sectional view illustrating a method for forming a structure body functioning as a mirror and a semiconductor film having side surfaces over an insulating surface. FIG. 10 is a cross-sectional view illustrating a method for forming a crystalline semiconductor film using a structure functioning as a mirror. FIG. 10 is a cross-sectional view illustrating a method for forming a structure body functioning as a mirror and a semiconductor film having side surfaces over an insulating surface. It is sectional drawing explaining the method of forming the structure which functions as a prism on an insulating surface. FIG. 10 is a cross-sectional view illustrating a method for forming a crystalline semiconductor film using a structure functioning as a prism. 4A and 4B are diagrams for describing a method for forming a transistor, in which FIG. 4A is a top view and FIG. 4B is a cross-sectional view taken along line B-B ′ in FIG. (C) is a cross-sectional view of the thin film transistor, taken along C-C ′ in (A). FIG. 12 is a cross-sectional view of a thin film transistor taken along C-C ′ in FIG. It is a figure for demonstrating the method of forming a transistor. It is a figure for demonstrating the method of forming a transistor. It is a graph of the reflectance, the transmittance | permeability, and the absorptivity of an amorphous silicon film with respect to the light of wavelength 532nm. It is a figure for demonstrating the method of forming a non-volatile memory element. It is a figure for demonstrating the method of forming a non-volatile memory element. It is a block diagram of a semiconductor device having a wireless communication function. 6A and 6B illustrate a method for manufacturing a semiconductor device having a wireless communication function. 6A and 6B illustrate a method for manufacturing a semiconductor device having a wireless communication function. 6A and 6B illustrate a method for manufacturing a semiconductor device having a wireless communication function. 6A and 6B illustrate a method for manufacturing a semiconductor device having a wireless communication function. 6A and 6B illustrate a method for manufacturing a semiconductor device having a wireless communication function. 6A and 6B illustrate a method for manufacturing a semiconductor device having a wireless communication function. FIG. 11 is a diagram for describing a method for using a semiconductor device having a wireless communication function. It is a figure which shows the structural example of a liquid crystal module, (A) is a front view, (B) is sectional drawing. It is a figure which shows the structural example of EL module, (A) is a front view, (B) is sectional drawing. FIG. 18 is an external view of a semiconductor device including a liquid crystal module or an EL module in a display portion.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Substrate 11 Insulating film 12 Side surface of semiconductor film 12a having side surface 13 Structure (structure having tapered portion) functioning as mirror
13a Reflecting surface 13b Tapered portion 14 Laser beam 15 Crystalline semiconductor 16 Insulating film 31 Structure functioning as prism (structure having reverse tapered portion)
201 substrate 202 insulating film 204 island-like semiconductor film 205 insulating film 206 mask insulating film 207 metal film 208 structure 209 laser beam 210 crystalline semiconductor film 211 insulating film 213 structure 214 mask insulating film 215 metal film 216 metal film 226 insulating film 227 resist mask 228 structure 401 substrate 402 insulating film 404 island-like semiconductor film 408 structure 410 island-like crystalline semiconductor film 412 gate insulating film 413 gate electrode 414 interlayer insulating film 415 electrode 428 structure 434 island-like semiconductor film 438 structure

Claims (8)

Forming a semiconductor film having a side surface having a thickness of 40 nm or less , and a structure having a reflective surface facing the side surface of the semiconductor film;
By irradiating a laser beam from above the semiconductor film and the structure, the laser beam is incident from an upper surface and a side surface of the semiconductor film, and the semiconductor film is crystallized to form a crystalline semiconductor film,
Forming a semiconductor device having a channel formation region in the crystalline semiconductor film,
The laser beam, a method for manufacturing a semiconductor device, characterized in that for entering from the side surface of the semiconductor film Rukoto is reflected by the reflecting surface of the structure to the semiconductor film. In claim 1,
Forming an insulating film covering the surface of the semiconductor film;
A method for manufacturing a semiconductor device, comprising: removing the insulating film after irradiating the laser beam in a state where the semiconductor film is covered with the insulating film. Forming an island-shaped semiconductor film having a side surface of 40 nm or less on the insulating surface;
Forming an insulating film on the island-shaped semiconductor film and the insulating surface;
Etching the insulating film into a predetermined shape to form a mask insulating film covering the island-shaped semiconductor film,
Forming a metal film on the mask insulating film and the insulating surface so as not to contact the island-shaped semiconductor film,
Etching the metal film to form a structure having a reflective surface facing the side surface of the island-shaped semiconductor film,
By irradiating a laser beam from above the island-shaped semiconductor film and the structure, the laser beam is incident from the upper surface and the side surface of the island-shaped semiconductor film, and the island-shaped semiconductor film is crystallized to form island-shaped crystals. Forming a conductive semiconductor film,
Removing the structure,
Forming a semiconductor element having a channel formation region in the island-shaped crystalline semiconductor film;
The method for manufacturing a semiconductor device, wherein the laser beam is incident on the semiconductor film from a side surface of the semiconductor film by being reflected by a reflecting surface of the structure body. Forming an island-shaped semiconductor film having a side surface of 40 nm or less on the insulating surface;
Forming an insulating film on the island-shaped semiconductor film and the insulating surface;
Etching the insulating film into a predetermined shape to form a mask insulating film and a structure covering the island-shaped semiconductor film,
Forming a metal film on the mask insulating film, the structure and the insulating surface so as not to contact the island-shaped semiconductor film,
Etching the metal film to leave the metal film covering the surface of the structure, thereby forming a reflective surface on the surface of the structure facing the side surface of the island-shaped semiconductor film,
By irradiating a laser beam from above the island-shaped semiconductor film and the structure, the laser beam is incident from the upper surface and the side surface of the island-shaped semiconductor film, and the island-shaped semiconductor film is crystallized to form island-shaped crystals. Forming a conductive semiconductor film,
Removing the structure,
Forming a semiconductor element having a channel formation region in the island-shaped crystalline semiconductor film;
The method for manufacturing a semiconductor device, wherein the laser beam is incident on the semiconductor film from a side surface of the semiconductor film by being reflected by a reflecting surface of the structure body. In claim 3 or 4,
A method for manufacturing a semiconductor device, wherein the mask insulating film is removed after irradiating the laser beam without removing the mask insulating film and covering the island-shaped semiconductor film with the mask insulating film. In any one of Claims 1 thru | or 5 ,
Wherein the structure has a tapered portion, a method for manufacturing a semiconductor device which is characterized that you form the reflective surface on the inclined surface of the tapered portion of the structure. In any one of Claims 1 thru | or 5 ,
The method for manufacturing a semiconductor device wherein the structure has a reverse taper portion, characterized that you form the reflective surface on the inclined surface of the reverse taper portion of said structure. In any one of claims 1 to 7,
The method of manufacturing a semiconductor device, wherein the laser beam is a beam emitted from a continuous wave laser, a pseudo continuous wave laser, or a pulsed laser having an oscillation frequency of 10 MHz or more.

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