JP5222450B2 - Laser irradiation apparatus and method for manufacturing semiconductor device - Google Patents

Description

  The present invention relates to a processing method for making the energy distribution of a laser beam uniform in a specific region. Further, a laser irradiation apparatus for annealing a semiconductor film using a laser beam (hereinafter referred to as laser annealing) (an apparatus including an optical system for guiding a laser and a laser beam output from the laser to an object to be processed). About. Further, the present invention relates to a method for manufacturing a semiconductor device manufactured by including the laser annealing in a process. Note that in this specification, a semiconductor device refers to all devices that can function by utilizing semiconductor characteristics, and includes an electro-optical device such as a liquid crystal display device or an EL display device and an electronic device including the electro-optical device as a component. Assume that the device is also in that category.

  In recent years, an amorphous semiconductor film or a crystalline semiconductor film (a semiconductor film having crystallinity such as polycrystalline or microcrystalline) that is formed over an insulating substrate such as glass, that is, a non-single-crystal semiconductor film is used. Techniques for performing laser annealing to crystallize or improve crystallinity have been widely studied. A silicon film is often used as the semiconductor film.

  A glass substrate is inexpensive and rich in workability as compared with a quartz substrate that has been conventionally used. Because of these properties, glass is often used for manufacturing large-area substrates. This is the reason for the above research. In addition, the reason why lasers are used favorably for crystallization is that the melting point of the glass substrate is low. The laser can give high energy only to the non-single crystal film without raising the temperature of the substrate so much.

In order to crystallize the amorphous semiconductor film by heat, a heating temperature of 600 ° C. or more and a heating time of 10 hours or more, preferably 20 hours or more are required. An example of a substrate that can withstand this crystallization condition is a quartz substrate. However, the quartz substrate is expensive and poor in workability, and it is very difficult to process a large area. Increasing the area of the substrate is an indispensable element for increasing production efficiency. In recent years, there has been a significant movement to increase the area of a substrate to improve production efficiency, and a newly constructed production factory line is becoming standard with a substrate size of 600 mm × 720 mm.

Processing a quartz substrate on such a large-area substrate is difficult with current technology, and even if possible, it is expensive and not industrial. On the other hand, glass is an example of a material that can easily produce a large-area substrate. There is a glass substrate called, for example, Corning 7059. Corning 7059 is very inexpensive, has good processability, and is easy to increase in area. However, Corning 7059 has a strain point temperature of 593 ° C., and there was a problem with heating above 600 ° C.

One glass substrate is Corning 1737, which has a relatively high strain point temperature. The strain point temperature is as high as 667 ° C. Even when an amorphous semiconductor film was formed on Corning 1737 and the temperature of the amorphous semiconductor film was maintained at 600 ° C. for 20 hours, the substrate was not deformed so as to affect the manufacturing process. Thereby, the amorphous semiconductor film was crystallized. However, the heating time of 20 hours is too long for the production process, and the heating temperature of 600 ° C. is preferably as low as possible from the viewpoint of cost.

In order to solve such problems, a new crystallization method has been devised. Details of the method are described in JP-A-7-183540. Here, the method will be briefly described. First, a trace amount of an element such as nickel, palladium, or lead is added to the amorphous semiconductor film. As the addition method, a plasma treatment method, a vapor deposition method, an ion implantation method, a sputtering method, a solution coating method, or the like may be used. After the addition, for example, when the amorphous semiconductor film is placed in a nitrogen atmosphere at 550 ° C. for 4 hours, a polycrystalline semiconductor film having good characteristics can be obtained. The optimum heating temperature for crystallization, opening during heating, and the like depend on the amount of the element added and the state of the amorphous semiconductor film.

In the above, the example of the crystallization method of the amorphous semiconductor film by heating was described. On the other hand, crystallization by laser annealing can give high energy only to the amorphous semiconductor film without increasing the temperature of the substrate so much. Can also be used.

Lasers often used for laser annealing are excimer laser and Ar laser. A laser beam of high output pulse oscillation is processed by an optical system so as to form a square spot of several centimeters square or a linear shape of, for example, a length of 10 cm or more on the irradiated surface, and the irradiation position of the laser beam is determined. In contrast, the method of performing laser annealing by scanning relatively is favorably used because of its high productivity and excellent mass production. In particular, when a laser beam having a linear laser beam shape on the surface to be irradiated (hereinafter referred to as a linear beam) is used, it is different from the case of using a spot laser beam that requires front / rear / right / left scanning. Since the entire irradiated surface can be irradiated by scanning only in the direction perpendicular to the linear direction of the linear beam, the productivity is high. The reason for scanning in the direction perpendicular to the line direction is that it is the most efficient scanning direction. Due to this high productivity, the use of a linear beam obtained by processing a high-power laser with an appropriate optical system is becoming the mainstream for laser annealing.

  FIG. 2 shows an example of an optical system for processing the shape of the laser beam into a linear shape on the irradiated surface. The optical system not only processes the shape of the laser beam into a linear shape, but also achieves uniformization of the energy of the laser beam on the irradiated surface. In general, an optical system that makes beam energy uniform is called a beam homogenizer.

First, the side view of FIG. 2 will be described. The laser beam emitted from the laser oscillator 201 is divided by the cylindrical lens array 202 in a direction perpendicular to the traveling direction of the laser beam. In the present specification, the perpendicular direction is referred to as a short direction. In FIG. 2, there are four divisions. These divided laser beams are once combined into one laser beam by the cylindrical lens 204. Further, the light is reflected by the mirror 206, and then again combined into one laser beam on the irradiation surface 208 by the doublet cylindrical lens 207. The doublet cylindrical lens refers to a lens composed of two cylindrical lenses. As a result, the energy in the short direction of the linear beam is made uniform, and the length in the short direction is determined.

Next, the top view of FIG. 2 will be described. The laser beam emitted from the laser oscillator 201 is divided by the cylindrical lens array 203 into a direction perpendicular to the traveling direction of the laser beam and perpendicular to the short direction. The direction is referred to as the long direction in the present specification. In FIG. 2, there are seven divisions. Thereafter, the laser beam is combined into one at the irradiation surface 208 by the cylindrical lens 205. Thereby, the energy in the longitudinal direction of the linear beam is made uniform, and the length in the longitudinal direction is determined.

The above lenses are made of synthetic quartz in order to cope with the excimer laser. In addition, an antireflection coating is applied to the surface so that the excimer laser can be transmitted well. As a result, the transmittance of the excimer laser per lens became 99% or more.

Laser annealing is performed on the entire surface of the non-single-crystal semiconductor film to crystallize or improve crystallinity by irradiating the linear beam processed by the above optical system while gradually shifting in the short direction. be able to.

Since the crystalline semiconductor film obtained by the laser annealing is made of many crystal grains, it is called a polycrystalline semiconductor film. A polycrystalline semiconductor film has very high mobility compared to an amorphous semiconductor film. Therefore, when a polycrystalline semiconductor film is used, for example, a monolithic liquid crystal electro-optical device (on a single substrate for pixel driving) that cannot be realized by a semiconductor device manufactured using a conventional amorphous semiconductor film. And a semiconductor device in which a thin film transistor (TFT) for a driver circuit is manufactured. As described above, the polycrystalline semiconductor film is a semiconductor film having very high characteristics as compared with the amorphous semiconductor film.

In addition to the method described above, there is a method of performing crystallization by laser annealing after crystallization by heating the amorphous semiconductor film. When this method is performed, the characteristics as a semiconductor film may be improved compared to the case where crystallization is performed only by heating or laser annealing. In order to obtain high characteristics, it is necessary to optimize heating conditions and laser annealing conditions. For example, when a thin film transistor (TFT) is manufactured by a known method using a polycrystalline semiconductor film obtained by the above method, the electrical characteristics of the TFT are greatly improved.

Problems to be solved by the invention

In order to manufacture a semiconductor film having higher electrical characteristics at a lower cost, a laser annealing technique has become indispensable. However, the performance of laser oscillators is still insufficient for mass production, leaving many problems to be solved. One of the problems is the maintainability of the apparatus used for laser annealing. In order to perform laser annealing of a semiconductor film, at least a laser oscillator, an optical system that uniformizes the energy distribution of the laser beam and processes it into a desired shape, a stage on which the semiconductor film is installed, and a robot that transports the semiconductor film are at least Necessary.

An excimer laser is often used as the laser oscillator. An excimer laser emits ultraviolet light, and therefore has a very high absorbability with respect to a silicon film, which is a typical semiconductor film, and has a high output and thus has high productivity. However, the excimer laser is very expensive and has a short apparatus life, and it is necessary to frequently replace parts and periodically replace gas necessary for oscillation, which requires a lot of maintenance. The cost generated by this is enormous, and there is an urgent need to develop a laser annealing apparatus to replace the excimer laser.

In the late 1990s, various lasers were newly developed or improved, and the demand for lasers increased rapidly. Among these lasers, the YAG laser is regarded as suitable for laser annealing of semiconductor films. In the early stages when laser annealing of semiconductor films began, there was a movement to use YAG lasers for crystallization of semiconductor films, but the output stability was poor and the output was smaller than that of excimer lasers. The excimer laser was given its status because it had to be converted into waves.

However, in recent years, the output of YAG laser has been rapidly increased and the stability of the output has been increased. Therefore, application of YAG laser to laser annealing has been attempted again. When used for crystallization of a semiconductor film, the YAG laser must be converted into a harmonic due to the absorption coefficient of the semiconductor film, but a sufficient output can be secured even after the conversion.

The advantages of YAG laser are mainly good maintainability, compactness and low price. Since the YAG laser is a solid-state laser, it does not use a gas like an excimer laser, so there is no need for replacement due to deterioration of the excitation source. The lifetime of the solid laser excitation source (rod) is said to be 20 years or more. Also, the number of parts required for laser oscillation is very small compared to the excimer laser.

Although the advantages of YAG laser are listed above, there are still many problems to be solved. First, since the oscillation frequency is lower than that of an excimer laser, productivity is low. This is because in a flash lamp-pumped YAG laser, if the temperature of the rod rises more than necessary, the thermal lens effect becomes remarkable, the shape of the laser beam becomes remarkably worse, and a high frequency is difficult to obtain. In that regard, the recently, YAG laser LD excitation which can suppress an increase in the temperature of the rod (laser diode excitation) have been developed, with the prospect of solving.

Another problem is the coherence of the YAG laser. In general, a laser is excellent in interference. Therefore, when a linear beam is obtained by dividing and combining laser beams into a beam having uniform energy, interference occurs in the linear beam and a standing wave is generated. However, since the excimer laser has a coherent length of several tens of μm, which is very short for a laser, interference hardly occurs and it is difficult to confirm the standing wave.

On the other hand, since the coherent length of the YAG laser is around 1 cm, the standing wave becomes very strong. FIG. 3 shows a standing wave generated in the YAG laser beam divided into two and synthesized. The energy distribution is obtained by a CCD camera, and the sine curve pattern can be clearly seen.

  An object of the present invention is to make the energy distribution of a laser beam having high coherence uniform. The present invention is particularly effective when uniformizing the energy distribution of a laser beam having a relatively long coherent length, such as a YAG laser, YVO4 laser, or YLF laser.

Means for solving the problem

The present invention provides a method of manufacturing a semiconductor device using a method of reducing interference fringes of a linear beam formed by a beam homogenizer.

  The laser can make the polarization of the laser beam uniform and make it linearly polarized light. In general, it is known that interference fringes do not occur even when laser beams having mutually orthogonal polarization directions are combined. Alternatively, a circularly polarized laser beam may be used. Circularly polarized laser beams do not interfere when the rotational directions of the circularly polarized light are different from each other. In this way, the lights whose polarization directions are independent from each other do not interfere with each other. By utilizing this property, the intended effect of the present invention can be obtained.

Therefore, if the laser beams whose polarization directions are orthogonal to each other are synthesized and made uniform, no interference occurs. Since YAG lasers can emit a linearly polarized laser beam, the laser beam is divided into two parts, nothing is performed on one of the two divided laser beams, and the polarization direction is rotated by 90 ° for the other. Therefore, if a λ / 2 plate is inserted, laser beams whose polarization directions are orthogonal to each other can be formed. However, since this method can only divide into two, it may be insufficient for uniformization. Therefore, the present method is combined with other methods to increase the number of divisions and to devise sufficient uniformity.

  In order to obtain a linear beam with uniform energy using a highly coherent laser, it is preferable to make the linear beam uniform in both the long and short directions. Therefore, it is preferable to synthesize at least two divided by two, that is, four divided laser beams into one to form a uniform linear beam. The first important thing when forming a uniform linear beam is to make the energy distribution in the longitudinal direction uniform. This is because the uniformity in the longitudinal direction is directly reflected in the uniformity of laser annealing in the longitudinal direction. On the other hand, the uniformity in the short direction is not as important as the uniformity in the long direction. This is because the uniformity of laser annealing can be increased by overlapping linear beams in the short direction. Therefore, the linear beam is made uniform in the short direction by combining two laser beams whose polarization directions are orthogonal to each other, and the linear beam in the long direction is made uniform by other methods. To do.

Further, even when laser beams are emitted from the same light source, no interference occurs in a laser beam synthesized with an optical path difference equal to or greater than the coherent length. If this property is used, even if a laser beam of three or more parts is combined, the laser beam can be made uniform without causing interference. For example, an optical path difference can be created by inserting a plate having high transparency with respect to the laser beam into the optical path.

The optical system used in the present invention is required to have a very small aberration. This is because the high coherence of the laser beam is a source of creating a wavy energy distribution due to spherical aberration and the like. FIG. 6 shows the energy distribution of the laser beam of the YAG laser that passes through various cylindrical lenses. F in the figure is the ratio of the focal length to the aperture of the lens, and the smaller the F, the larger the spherical aberration.

FIG. 6A shows the energy distribution of the used YAG laser. This is a photograph of traces of direct irradiation of the amorphous silicon film with the YAG laser beam. There is no noticeable energy non-uniformity in the photograph of FIG. On the other hand, FIG. 6B shows a photograph in which the laser beam of the YAG laser is passed through a cylindrical lens of F = 7 and similarly irradiated to the amorphous silicon film. The striped pattern is clearly visible in the horizontal direction. This is the energy distribution caused by the spherical aberration of the cylindrical lens with F = 7. FIG. 6C is a view through a cylindrical lens with F = 20, and FIG. 6D is a view through a cylindrical lens with F = 100. The laser beam that has passed through the cylindrical lens with F = 7 is greatly affected by spherical aberration, and has a wavy energy distribution. On the other hand, the spherical aberration of the laser beam passed through the F = 20 cylindrical lens is relatively suppressed, and the wave-like energy distribution is not conspicuous. In addition, no wave-like energy distribution was observed in the laser beam that passed through the F = 100 cylindrical lens.

It should be noted that the F value described in the present specification is calculated with the range in which the laser beam is actually transmitted through the lens as the lens diameter. Therefore, when the size of the lens is larger than the size of the transmitted beam, the beam size is set as the aperture.

The configurations of the present invention are listed below.

  The structure of the invention relating to the laser beam processing method disclosed in the present specification is the laser beam processing method, wherein the laser beams have polarization directions that are independent of each other in a first direction perpendicular to the traveling direction of the laser beam. And splitting the two laser beams into one at or near the irradiation surface, and perpendicular to the traveling direction of the laser beam and perpendicular to the first direction. The laser beam is divided into a plurality of laser beams having different optical path lengths in two directions, and the plurality of laser beams are combined into one at or near the irradiation surface.

  In the above configuration, at least a λ / 2 plate is used to divide the laser beam into two laser beams having polarization directions that are independent of each other.

According to another configuration of the invention relating to the laser beam processing method disclosed in the present specification, in the linearly polarized laser beam processing method, the laser beam is moved in a first direction perpendicular to the traveling direction of the laser beam. Split into two laser beams having polarization directions that are perpendicular to each other;
The two laser beams are combined into one at or near the irradiation surface, and the laser beams are combined with each other in a second direction perpendicular to the traveling direction of the laser beam and perpendicular to the first direction. The laser beam is divided into a plurality of laser beams having different optical path lengths, and the plurality of laser beams are combined into one at or near the irradiation surface.

According to another aspect of the invention relating to a laser beam processing method, a linear beam processing method for homogenizing a linearly polarized laser beam at or near an irradiation surface is perpendicular to the traveling direction of the laser beam. In this direction, the laser beam is divided into two laser beams having polarization directions perpendicular to each other, and the two laser beams are combined into one at or near the irradiation surface, and the short direction of the linear beam The laser beam is divided into a plurality of laser beams having optical path lengths different from each other in a second direction perpendicular to the traveling direction of the laser beam and perpendicular to the first direction. The plurality of laser beams are combined into one at or near the irradiation surface, and the energy distribution in the longitudinal direction of the linear beam is averaged. It is characterized in that reduction.

  In each of the above configurations, at least a λ / 2 plate is used to divide the laser beam into two laser beams having polarization directions that are perpendicular to each other.

According to another configuration of the invention relating to the laser beam processing method disclosed in this specification, in the circularly polarized laser beam processing method, the laser beam is moved in a first direction perpendicular to the traveling direction of the laser beam. Splitting into two laser beams having circularly polarized light that are independent of each other, combining the two laser beams into one at or near the irradiation surface, perpendicular to the direction of travel of the laser beam, and The laser beam is divided into a plurality of laser beams having different optical path lengths in a second direction perpendicular to one direction, and the plurality of laser beams are combined into one at or near the irradiation surface. It is said.

  According to another aspect of the invention relating to the laser beam processing method, a linear beam processing method for uniformizing a circularly polarized laser beam at or near the irradiation surface is a first perpendicular to the traveling direction of the laser beam. The laser beam is divided into two laser beams having circularly polarized light that are independent of each other in the direction of, and the two laser beams are combined into one at or near the irradiation surface, so that the short direction of the linear beam The laser beam is divided into a plurality of laser beams having optical path lengths different from each other in a second direction perpendicular to the traveling direction of the laser beam and perpendicular to the first direction. , Combining the plurality of laser beams into one at or near the irradiation surface to uniformize the energy distribution in the longitudinal direction of the linear beam It is characterized in Rukoto.

  In each of the above structures, at least a λ / 2 plate is used to divide the laser beam into two laser beams having circularly polarized light that are independent of each other.

  In each of the above-described configurations, a plate having a high transmittance with respect to at least the laser beam is used to divide the laser beam into a plurality of laser beams having optical path lengths different from each other in the second direction. It is said.

  In each of the above structures, a cylindrical lens having at least an F value of 20 or more is used to divide the laser beam into a plurality of laser beams having different optical path lengths in the second direction.

  In each of the above structures, a cylindrical lens having at least an F value of 20 or more is used in order to combine the plurality of laser beams into one at or near the irradiation surface.

In each of the above-described structures, a laser beam emitted from one or a plurality of types selected from a YAG laser, a YVO ₄ laser, and a YLF laser is used as the laser beam.

  Further, the configuration of the invention relating to the laser irradiation apparatus disclosed in this specification is a laser irradiation apparatus that forms a laser beam having a uniform energy distribution at or near the irradiation surface, and is perpendicular to the traveling direction of the laser beam. A splitting unit that divides the laser beam into two laser beams having polarization directions that are independent of each other in a first direction, a combining unit that combines the two laser beams into one at or near the irradiation surface, and Splitting means for converting the laser beam into a plurality of laser beams having different optical path lengths in a second direction perpendicular to the traveling direction of the laser beam and perpendicular to the first direction; and the plurality of laser beams And a synthesizing unit that makes one at the irradiation surface or in the vicinity thereof.

  In the above-described configuration, the splitting unit that divides the laser beam into two laser beams having polarization directions that are independent of each other includes a λ / 2 plate.

  In addition, another configuration of the invention relating to the laser irradiation apparatus disclosed in the present specification is a laser irradiation apparatus that forms a laser beam having a uniform energy distribution on or near the irradiation surface, in the traveling direction of the laser beam. A splitting unit that splits the laser beam into two laser beams having polarization directions that are perpendicular to each other in a first direction that is perpendicular, and a combining unit that combines the two laser beams into one at or near the irradiation surface; Splitting means for converting the laser beam into a plurality of laser beams having different optical path lengths in a second direction perpendicular to the traveling direction of the laser beam and perpendicular to the first direction; And combining means for bringing the laser beam to one at or near the irradiation surface.

  Another aspect of the invention relating to the laser irradiation apparatus is a laser irradiation apparatus for forming a linear beam having a uniform energy distribution at or near the irradiation surface, which is perpendicular to the traveling direction of the laser beam. Splitting the laser beam into two laser beams having polarization directions perpendicular to each other in one direction, and combining the two laser beams into one at or near the irradiation surface, A plurality of synthesizing means for making the energy distribution in the direction uniform, and a plurality of optical path lengths different from each other in the second direction perpendicular to the traveling direction of the laser beam and perpendicular to the first direction. Splitting means for forming a laser beam, and a plurality of the laser beams in one at or near the irradiation surface, and the longitudinal direction of the linear beam It is characterized by having a synthesizing means for homogenizing the energy distribution.

  In each of the above-described configurations, the dividing means for converting the laser beam into two laser beams having polarization directions perpendicular to each other includes a λ / 2 plate.

In addition, another configuration of the invention relating to the laser irradiation apparatus disclosed in the present specification is a laser irradiation apparatus that forms a laser beam having a uniform energy distribution on or near the irradiation surface, in the traveling direction of the laser beam. Splitting means for converting the laser beam into two laser beams having circularly polarized light that are independent of each other in a first direction that is perpendicular, and combining means for combining the two laser beams into one at or near the irradiation surface; Splitting means for converting the laser beam into a plurality of laser beams having optical path lengths different from each other in a second direction perpendicular to the traveling direction of the laser beam and perpendicular to the first direction;
And a combining unit that combines the plurality of laser beams into one at or near the irradiation surface.

  Another aspect of the invention relating to the laser irradiation apparatus is a laser irradiation apparatus that forms a linear beam having a uniform energy distribution at or near the irradiation surface, the first being perpendicular to the traveling direction of the laser beam. Splitting the laser beam into two laser beams having circularly polarized light that are independent of each other in the direction of, and combining the two laser beams into one at or near the irradiation surface, And a plurality of lasers having optical path lengths different from each other in a second direction perpendicular to the traveling direction of the laser beam and perpendicular to the first direction. A beam splitting unit, and the plurality of laser beams are combined into one in the vicinity of the irradiation surface or in the vicinity of the longitudinal direction of the linear beam. It is characterized by having a synthesizing means for uniformizing the energy distribution.

  In each of the above-described configurations, the splitting means for converting the laser beam into two laser beams having circularly polarized light that are independent of each other has a λ / 2 plate.

  Further, in each of the above-described configurations, the dividing means for converting the laser beam into a plurality of laser beams having optical path lengths different from each other includes a plate having a high transmittance with respect to the laser beam.

  Further, in each of the above-described configurations, the dividing means for converting the laser beam into a plurality of laser beams having optical path lengths different from each other includes a cylindrical lens having an F value of 20 or more.

  Further, in each of the above-described configurations, the combining unit that combines the plurality of laser beams into one at or near the irradiation surface includes a cylindrical lens having an F value of 20 or more.

In each of the above structures, the laser beam is a laser beam oscillated from one or a plurality of types selected from a YAG laser, a YVO ₄ laser, and a YLF laser.

  According to another aspect of the invention related to a method for manufacturing a semiconductor device disclosed in this specification, in the method for manufacturing a semiconductor device in which a TFT is provided over a substrate, the laser in the first direction perpendicular to the traveling direction of the laser beam. Splitting the beam into two laser beams having polarization directions that are independent of each other, combining the two laser beams into one at or near the irradiated surface, perpendicular to the direction of travel of the laser beam, and Dividing the laser beam into a plurality of laser beams having different optical path lengths in a second direction perpendicular to the first direction, and combining the plurality of laser beams into one at or near the irradiation surface; A linear beam having a long direction parallel to the second direction is formed, and irradiation is performed while moving the linear beam relative to the non-single crystal semiconductor film. It is characterized in Rukoto.

  In the above configuration, at least a λ / 2 plate is used to divide the laser beam into two laser beams having polarization directions that are independent of each other.

  In the above structure, a plate having a high transmittance with respect to at least the laser beam is used to divide the laser beam into a plurality of laser beams having different optical path lengths.

  In the above configuration, a cylindrical lens having at least an F value of 20 or more is used to divide the laser beam into a plurality of laser beams having different optical path lengths.

  Further, in the above configuration, in order to form a linear beam in which the direction parallel to the second direction is a long direction by combining the plurality of laser beams into one at or near the irradiation surface, A cylindrical lens having at least an F value of 20 or more is used.

In each of the above structures, a laser beam oscillated from one or a plurality of types selected from a YAG laser, a YVO ₄ laser, and a YLF laser is used as the laser beam.

  As described above, the present invention makes it possible to reduce the coherence of the laser beam in the energy distribution of the coherent laser beam and remarkably improve the uniformity of the energy distribution. In addition, when the present invention is combined with a solid-state laser and used in a semiconductor film crystallization process, significant cost reduction can be expected. In addition, a TFT is manufactured using the semiconductor film thus obtained, and in an electro-optical device and a semiconductor device typified by an active matrix liquid crystal display device manufactured using the TFT, sufficient operating characteristics and Reliability can be realized.

  FIG. 1 shows an optical system capable of reducing the coherence and obtaining a linear beam having a uniform energy distribution according to the present invention.

First, the top view of FIG. 1 will be described. The laser beam emitted from the laser oscillator 101 is incident on a stepped quartz plate 109 in order to create a stepped optical path difference in a direction perpendicular to the traveling direction of the laser beam. The stepped quartz plate 109 is used for the purpose of making optical path differences between the laser beams passing through the steps of the steps. It is important that the optical path difference thus formed is equal to or greater than the coherent length of the laser beam to be used. This is because even if the same region is irradiated with a laser beam having an optical path difference longer than the coherent length, the coherence is very weak.

In FIG. 1, a quartz plate 109 having six steps is used, so that seven laser beams having seven types of optical path lengths can be formed. That is, six laser beams pass through the quartz plate 109 and the other one does not go through the quartz plate 109. The seven laser beams are incident on the seven cylindrical lenses included in the cylindrical lens array 103, respectively. The cylindrical lens array 103 divides the laser beams having optical path differences into seven. The laser beam divided into seven is combined into one on the irradiation surface 108 by the cylindrical lens 105. At this time, if a sufficient optical path difference is given to each of the divided laser beams by the action of the quartz plate 109, the laser beam does not cause strong interference on the irradiation surface 108. Thereby, the energy in the longitudinal direction of the linear beam is made uniform, and the length in the longitudinal direction is determined.

Next, it demonstrates along a side view. It is assumed that the laser beam emitted from the laser oscillator 101 is a linearly polarized beam. The laser beam enters the λ / 2 plate 110 and is processed into two laser beams whose polarization planes are perpendicular to each other. The two laser beams are incident on two cylindrical lenses included in the cylindrical lens array 102, respectively. The laser beam divided into two by the cylindrical lens array 102 is combined into one on the irradiation surface 108 by the cylindrical lenses 104 and 106. The mirror 107 in the middle of the optical path is for making the irradiated surface coincide with the horizontal plane. If the optical path of the laser beam is in the vertical direction from the beginning, the mirror 107 need not be used. Alternatively, if the irradiated surface is perpendicular to the ground, the mirror 107 is not necessary. In this case, a means for fixing the irradiation target to a wall perpendicular to the ground is required. Thereby, the energy in the short direction of the linear beam is made uniform, and the length in the short direction is determined.

In the above example, the laser beam emitted from the laser oscillator is linearly polarized, but a circularly polarized laser beam may be used. Circularly polarized laser beams do not interfere when the rotational directions of the circularly polarized light are different from each other. By utilizing this property, the intended effect of the present invention can be obtained. As described above, there are two laser beams which do not interfere with each other even if the laser beam has coherence because the polarization state is different. In the present specification, these beams are referred to as beams whose polarization directions are independent from each other.

As the laser oscillator 101, a laser whose polarization plane is aligned, such as a YAG laser, a YVO ₄ laser, or a YLF laser, is used. Considering the throughput when used in a production factory, it is preferable to use a high repetition pulse laser. In order to obtain a high repetition rate laser with a solid state laser, it is important not to raise the temperature of the rod. There is an LD-pumped solid-state laser that can suppress the temperature rise of the rod. In particular, when considering mass production, it is very useful to combine the method of uniformizing the energy distribution of the laser beam of the present invention with an LD-pumped solid-state laser. Note that when a plurality of types of lasers selected from a YAG laser, a YVO ₄ laser, and a YLF laser are used, it is possible to further reduce the interference of the laser beam on or near the irradiated surface.

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

Example 1
In this embodiment, a method for forming a semiconductor device by forming an amorphous silicon film over a glass substrate and crystallizing the amorphous silicon film by a laser irradiation method disclosed in the present invention will be described.

First, an example of a method for forming an amorphous silicon film will be described. First, a 5-inch square Corning 1737 substrate is cleaned to remove dust on the substrate surface. Next, a silicon nitride oxide film is grown to a thickness of 100 nm and an amorphous silicon film is grown to a thickness of 55 nm on the substrate by a plasma CVD apparatus. Note that in this specification, a silicon nitride oxide film is an insulating film expressed by SiOxNy and indicates an insulating film containing silicon, oxygen, and nitrogen at a predetermined ratio. In some cases, the amorphous silicon film contains a large amount of hydrogen. In this case, the hydrogen content is reduced by heat treatment or the like to increase the laser resistance of the amorphous silicon film. In this case, for example, the amorphous silicon film may be heated in a nitrogen atmosphere at 500 ° C. for 1 hour.

Next, details of the optical system used in this embodiment will be described with reference to FIG. First, it demonstrates from a top view. The laser oscillator 1401 is a flash lamp pumped YAG laser. In this embodiment, in order to anneal the amorphous silicon film, the laser beam emitted from the YAG laser is converted into a second harmonic having a large absorption with respect to the amorphous silicon film using a nonlinear optical element. . When converted to the second harmonic, the output is 800 mJ per pulse. The maximum frequency is 30 Hz. The laser beam emitted from the laser oscillator 1401 has a size of φ10 mm. Since it is very small and difficult to process, the beam expander 1402 expands the linear beam in the longitudinal direction. In the case of this embodiment, the laser beam is expanded in one direction at an expansion ratio of 3.5 times. As the beam expander 1402, a beam expander whose aberration is suppressed as much as possible is used.

The laser beam processed into an ellipse having a major axis of 35 mm and a minor axis of 10 mm by the beam expander is processed into seven laser beams having optical path differences through a quartz plate 1403 processed in a staircase shape. That is, there are 6 (7-1) steps. The thickness of the stairs was 15 mm at each stage. Therefore, the thickness of the quartz plate 1403 is 90 mm at the thickest part. Thereby, the optical path difference of the seven laser beams is 7 mm at the minimum. This is almost equal to the coherent length of the present YAG laser.

Seven laser beams emitted from the quartz plate 1403 are incident on cylindrical lenses constituting the cylindrical lens array 1405, respectively. The laser beams divided by the cylindrical lens array 1405 are combined into one by the cylindrical lens 1406 on the irradiation surface 1410 (see side view). Thereby, the energy is made uniform in the longitudinal direction of the linear beam. Also, the length of the linear beam is determined. Since the seven laser beams have optical path differences that are greater than or equal to the coherent length, interference at the irradiation surface 1410 is very weak. The mirror 1408 is used to change the traveling direction of the laser beam in the direction perpendicular to the paper surface. By the mirror 1408, a linear beam is formed on a horizontal plane, and an irradiation target can be placed on the horizontal plane.

Next, FIG. 4 will be described along a side view. The laser oscillator 1401 is designed to emit linearly polarized light. In the side view, the polarization direction is assumed to be parallel to the paper surface and perpendicular to the traveling direction of the laser beam. The laser beam is processed into an ellipse by the beam expander 1402 and then enters the λ / 2 plate 1404. The λ / 2 plate 1404 has a rectangular shape and is installed so that one side of the λ / 2 plate 1404 matches the major axis of the elliptical laser beam. Therefore, only half of the laser beam is incident on the λ / 2 plate. The polarization direction of the laser beam is rotated by 90 ° by the λ / 2 plate 1404. As a result, the laser beam is divided into a horizontally polarized light beam and a vertically polarized light beam. The horizontally-polarized laser beam and the vertically-polarized laser beam are incident on the cylindrical lenses constituting the cylindrical lens array 1407, respectively. As a result, the laser beam is divided into two and is combined into one on the irradiation surface 1410 by the cylindrical lens 1409. Thereby, the energy in the short direction of the linear beam is made uniform. Further, the length of the linear beam in the short direction is determined. The mirror 1408 is used to make the irradiation surface 1410 horizontal.

Next, specific specifications of each lens will be described. The cylindrical lens array 1405 is formed by combining seven cylindrical lenses having a width of 5 mm, a length of 30 mm, a thickness of 4 mm, and a focal length of 400 mm. The cylindrical lens 1406 has a width of 60 mm, a length of 30 mm, a thickness of 5 mm, and a focal length of 4800 mm. The cylindrical lens 1406 is arranged 400 mm behind the cylindrical lens array 1405. The cylindrical lens array 1407 is formed by combining two lenses having a width of 5 mm, a length of 60 mm, a thickness of 5 mm, and a focal length of 2000 mm. The cylindrical lens array 1407 is disposed 400 mm behind the cylindrical lens 1406. The mirror 1408 is disposed 3600 mm behind the cylindrical lens array 1407. The mirror 1408 is used to change the traveling direction of the 90 ° laser beam. The size of the mirror 1408 is sufficiently large so that all the laser beams can enter. In the case of the present embodiment, it is sufficient that the size of the mirror surface is 120 mm × 120 mm.

A cylindrical lens 1409 is disposed behind the mirror 1408. The cylindrical lens 1409 has a width of 50 mm, a length of 130 mm, a thickness of 15 mm, and a focal length of 400 mm. An irradiation surface 1410 is disposed at 400 mm behind the cylindrical lens 1409.

With the configuration of the optical system described above, a linear beam having a length of 120 mm in the long direction and a length of 1 mm in the short direction can be formed on the irradiation surface 1410. Note that the specifications and arrangement of the optical system described above are approximate guidelines. When the practitioner actually produces a linear beam, it is necessary to take into account some errors and arrange the optical system. The irradiation surface 1410 is provided with a stage on which the amorphous semiconductor film to be irradiated with the laser beam can be placed. By operating the stage in one direction, the laser beam is applied to the entire surface of the amorphous semiconductor film. Can be irradiated. The one direction is perpendicular to the longitudinal direction of the linear beam.

Irradiation conditions for irradiating the amorphous semiconductor film to be irradiated with the laser beam with the laser beam and crystallizing the amorphous semiconductor film are described below. The energy density of the laser beam is 450 mJ / cm ^{2 on the} irradiation surface 1410. The operation speed of the stage is a constant speed of 3 mm / s, and the atmosphere at the time of laser beam irradiation is air. The oscillation frequency of the laser beam is 30 Hz. As a result, the laser beam is irradiated 10 times on the same region of the amorphous semiconductor film. As described above, the amorphous semiconductor film is crystallized by a series of operations.

A semiconductor device is manufactured based on the polycrystalline silicon film manufactured through the above steps. Semiconductor devices include thin film transistors (TFTs), diodes, optical sensors, and the like, all of which can be manufactured based on the polycrystalline silicon film. In addition to the polycrystalline silicon film, a compound semiconductor film such as a polycrystalline silicon germanium film may be applied.

(Example 2)
In this embodiment, an example in which a polycrystalline semiconductor film is irradiated with a linear beam and the polycrystalline semiconductor film is annealed is shown.

First, a method for manufacturing a polycrystalline semiconductor film will be described. First, a 5-inch square Corning 1737 substrate is cleaned to remove dust on the substrate surface. Next, a silicon nitride oxide film having a thickness of 100 nm and an amorphous silicon film having a thickness of 55 nm are formed on the substrate by a plasma CVD apparatus. Note that in this specification, a silicon nitride oxide film is an insulating film expressed by SiOxNy and indicates an insulating film containing silicon, oxygen, and nitrogen at a predetermined ratio. Next, using a method as described in JP-A-7-183540, a nickel acetate aqueous solution (concentration 5 ppm by weight, volume 5 ml) is applied to the surface of the amorphous silicon film by spin coating. And heating in a nitrogen atmosphere at a temperature of 500 ° C. for 1 hour and further in a nitrogen atmosphere at a temperature of 550 ° C. for 4 hours. As a result, the amorphous silicon film changes to a polycrystalline silicon film.

Laser annealing is performed on the obtained polycrystalline silicon film. The laser annealing method is the same as that described in Example 1. Although there are some differences in conditions when the amorphous silicon film is irradiated with the linear beam and when the polycrystalline silicon film is irradiated with the linear beam, they are not significantly different. The optimal conditions need to be found by the practitioner through experimentation.

A semiconductor device is manufactured based on the polycrystalline silicon film manufactured through the above steps. Semiconductor devices include thin film transistors (TFTs), diodes, optical sensors, and the like, all of which can be manufactured based on the polycrystalline silicon film. In addition to the polycrystalline silicon film, a compound semiconductor film such as a polycrystalline silicon germanium film may be applied.

(Example 3)
In this embodiment, an example of a laser irradiation apparatus for mass production is shown along FIG. FIG. 5 is a top view of the laser irradiation apparatus.

The substrate is transferred from the load / unload chamber 1501 using a transfer robot arm 1503 installed in the transfer chamber 1502. First, the substrate is aligned in the alignment chamber 1504 and then transferred to the preheat chamber 1505. Here, for example, an infrared lamp heater is used to heat the substrate to a desired temperature, for example, about 300 ° C. in advance. Thereafter, a substrate is set in the laser irradiation chamber 1507 via the gate valve 1506. Thereafter, the gate valve 1506 is closed. The reason for raising the temperature of the substrate is to compensate for the lack of energy of the laser beam. In particular, when processing a large area substrate, it may be necessary to increase the length of the linear beam. In this case, if laser annealing is performed by increasing the temperature of the substrate, laser energy is usually required. It can be kept lower than the value.

After exiting the laser oscillator 1500, the laser beam is bent 90 ° downward by a mirror (not shown) installed directly above the quartz window 1510 via the optical system 1509, and is in the laser irradiation chamber 1507 via the quartz window 1510. It is processed into a linear beam on the irradiated surface. The laser beam is applied to the substrate placed on the irradiation surface. As the optical system 1509, the one described above may be used. Moreover, you may use the thing according to it.

Before the laser beam irradiation, the atmosphere of the laser irradiation chamber 1507 is pulled to a high vacuum (10 ⁻³ Pa) by using a vacuum pump 1511. Alternatively, a desired atmosphere is obtained using a vacuum pump 1511 and a gas cylinder 1512. The atmosphere may be an atmospheric component as described above, or He, Ar, H ₂ , or a mixed gas thereof.

Thereafter, the substrate is scanned with the moving mechanism 1513 while irradiating the laser beam, so that the substrate is irradiated with the linear beam. At this time, an infrared lamp (not shown) may be applied to the portion irradiated with the linear beam.

After the irradiation of the laser beam is completed, the substrate is carried to the cooling chamber 1508, and after slowly cooling the substrate, the substrate is returned to the load / unload chamber 1501 via the alignment chamber 1504. By repeating these series of operations, a number of substrates can be laser-annealed.

  Note that this embodiment can be used in combination with any one of the embodiment modes and other embodiments.

Example 4
In this embodiment, a method for manufacturing an active matrix substrate will be described with reference to FIGS. Note that in this specification, a substrate in which a driver circuit, a pixel portion including a pixel TFT and a storage capacitor are formed over the same substrate is referred to as an active matrix substrate for convenience.

  First, in this embodiment, a substrate 300 made of glass such as barium borosilicate glass represented by Corning # 7059 glass or # 1737 glass or aluminoborosilicate glass is prepared. Alternatively, the substrate 300 may be a quartz substrate, a silicon substrate, a metal substrate, or a stainless steel substrate on which an insulating film is formed. Alternatively, a plastic substrate having heat resistance that can withstand the processing temperature of this embodiment may be used.

Next, a base film 301 made of an insulating film such as a silicon oxide film, a silicon nitride film, or a silicon oxynitride film is formed over the substrate 300. In this embodiment, the base film 301 has a two-layer structure, but a single-layer film of the insulating film or a structure in which three or more layers are stacked may be used. The first layer of the base film 301 is a silicon oxynitride film 301a formed by using a plasma CVD method using SiH ₄ , NH ₃ , and N ₂ O as reaction gases. The thickness of the silicon oxynitride film 301a is 10 to 200 nm (preferably 50 to 100 nm). In this embodiment, a 50 nm thick silicon oxynitride film 301a (composition ratio Si = 32%, O = 27%, N = 24%, H = 17%) is formed. Next, the second layer of the base film 301 is a silicon oxynitride film 301b formed by using a plasma CVD method using SiH ₄ and N ₂ O as reaction gases. The thickness of the silicon oxynitride film 301b is 50 to 200 nm (preferably 100 to 150 nm). In this embodiment, a silicon oxynitride film 301b (composition ratio Si = 32%, O = 59%, N = 7%, H = 2%) having a thickness of 100 nm is formed.

  Next, a semiconductor layer 304 is formed over the base film. The semiconductor layer 304 is formed by forming a semiconductor film having an amorphous structure by a known means (sputtering method, LPCVD method, plasma CVD method, or the like), and then the crystallization treatment method (laser crystallization method, Alternatively, it is obtained by performing a method combining a thermal crystallization method using a catalyst such as nickel and a laser crystallization method. The thickness of the semiconductor layer 304 is 25 to 80 nm (preferably 30 to 60 nm). There is no limitation on the material of the crystalline semiconductor film, but the crystalline semiconductor film is preferably formed of silicon or a silicon germanium (SiGe) alloy. In this embodiment, a plasma CVD method is used to form a 55 nm amorphous silicon film, and then a solution containing nickel is held on the amorphous silicon film. This amorphous silicon film is subjected to a dehydrogenation process (500 ° C. nitrogen atmosphere, 1 hour), and further continuously subjected to a thermal crystallization process (550 ° C. nitrogen atmosphere, 4 hours). Further, in order to improve the crystallinity of the obtained crystalline silicon film, a laser annealing treatment method shown in the present invention is performed to form a crystalline silicon film. Then, this crystalline silicon film is patterned into a desired shape by a photolithography method to form semiconductor layers 402 to 406.

  Here, if necessary, a small amount of impurity element (boron or phosphorus) may be doped into the semiconductor layers 402 to 406 in order to control the threshold value of the TFT. The doping may be performed on the semiconductor layer 304 that is not patterned.

  Next, a gate insulating film 407 covering the semiconductor layers 402 to 406 is formed. The gate insulating film 407 is formed of an insulating film containing silicon with a thickness of 40 to 150 nm by using a plasma CVD method or a sputtering method. In this embodiment, a silicon oxynitride film (composition ratio Si = 32%, O = 59%, N = 7%, H = 2%) is formed to a thickness of 110 nm by plasma CVD. Needless to say, the gate insulating film is not limited to the silicon oxynitride film, and another insulating film containing silicon may be used as a single layer or a stacked structure.

When a silicon oxide film is used, TEOS (Tetraethyl Orthosilicate) and O ₂ are mixed by a plasma CVD method to a reaction pressure of 40 Pa, a substrate temperature of 300 to 400 ° C., and a high frequency (13.56 MHz) power density of 0. It can be formed by discharging at 5 to 0.8 W / cm ² . The silicon oxide film thus manufactured can obtain good characteristics as a gate insulating film by subsequent thermal annealing at 400 to 500 ° C.

Next, as illustrated in FIG. 7C, a first conductive film 408 with a thickness of 20 to 100 nm and a second conductive film 409 with a thickness of 100 to 400 nm are stacked over the gate insulating film 407. In this embodiment, a first conductive film 408 made of a TaN film with a thickness of 30 nm and a second conductive film 409 made of a W film with a thickness of 370 nm are stacked. The TaN film is formed by sputtering, and is sputtered in a nitrogen-containing atmosphere using a Ta target. The W film is formed by sputtering using a W target. In addition, it can be formed by a thermal CVD method using tungsten hexafluoride (WF ₆ ). In any case, in order to use as a gate electrode, it is necessary to reduce the resistance, and the resistivity of the W film is desirably 20 μΩcm or less. The resistivity of the W film can be reduced by increasing the crystal grains. However, when there are many impurity elements such as oxygen in the W film, the crystallization is hindered and the resistance is increased. In order to suppress the increase in resistance of the W film, a high-purity W (purity 99.9999%) target is preferably used. In addition, the W film is preferably formed with sufficient consideration so that impurities are not mixed in from the gas phase during the film formation. By these methods, the resistivity of the W film can be set to 9 to 20 μΩcm.

  In this embodiment, TaN is used for the first conductive film 408 and W is used for the second conductive film 409, but there is no particular limitation, and all of them are Ta, W, Ti, Mo, Al, Cu, Cr, Nd. You may form with the element selected from these, or the alloy material or compound material which has the said element as a main component. Alternatively, a semiconductor film typified by a polycrystalline silicon film doped with an impurity element such as phosphorus may be used. Further, an AgPdCu alloy may be used. In addition, the first conductive film is formed using a tantalum (Ta) film, the second conductive film is formed using a W film, the first conductive film is formed using a titanium nitride (TiN) film, and the second conductive film is formed. The first conductive film is formed of a tantalum nitride (TaN) film, the second conductive film is formed of an Al film, and the first conductive film is formed of a tantalum nitride (TaN) film. The second conductive film may be a combination of Cu films.

Next, resist masks 410 to 415 are formed by photolithography, and a first etching process for forming electrodes and wirings is performed. The first etching process is performed under the first and second etching conditions. In this embodiment, ICP (Inductively Coupled Plasma) etching method is used as the first etching condition, CF ₄ , Cl ₂ and O ₂ are used as etching gases, and each gas flow rate is 25 sccm, Etching is performed by generating a plasma by generating 500 W RF (13.56 MHz) power to the coil-type electrode at a pressure of 1 Pa at 25 sccm and 10 sccm. Here, a dry etching apparatus (Model E645- □ ICP) using ICP manufactured by Matsushita Electric Industrial Co., Ltd. may be used. 150 W RF (13.56 MHz) power is also applied to the substrate side (sample stage), and a substantially negative self-bias voltage is applied. The W film is etched under this first etching condition so that the end portion of the first conductive layer is tapered.

Thereafter, the masks 410 to 415 made of resist are changed to the second etching conditions without removing them, CF ₄ and Cl ₂ are used as etching gases, the respective gas flow rates are 30 sccm and 30 sccm, and the pressure is 1 Pa. A 500 W RF (13.56 MHz) power is applied to the coil-type electrode to generate plasma, and etching is performed for about 30 seconds. 20 W of RF (13.56 MHz) power is also applied to the substrate side (sample stage), and a substantially negative self-bias voltage is applied. Under the second etching condition in which CF4 and Cl2 are mixed, the W film and the TaN film are etched to the same extent. Note that in order to perform etching without leaving a residue on the gate insulating film, it is preferable to increase the etching time at a rate of about 10 to 20%.

  In the first etching process, the shape of the mask made of resist is made suitable, and the end portions of the first conductive layer and the second conductive layer are tapered due to the effect of the bias voltage applied to the substrate side. It becomes. The angle of this taper portion is 15 to 45 °. Thus, the first shape conductive layers 417 to 422 (the first conductive layers 417 a to 422 a and the second conductive layers 417 b to 422 b) composed of the first conductive layer and the second conductive layer by the first etching treatment. Form. Reference numeral 416 denotes a gate insulating film, and a region not covered with the first shape conductive layers 417 to 422 is etched and thinned by about 20 to 50 nm.

Then, a first doping process is performed without removing the resist mask, and an impurity element imparting n-type conductivity is added to the semiconductor layer. (FIG. 8A) The doping process may be performed by an ion doping method or an ion implantation method. The conditions of the ion doping method are a dose amount of 1 × 10 ^{13 to} 5 × 10 ¹⁵ atoms / cm ² and an acceleration voltage of 60 to 100 keV. In this embodiment, the dose is set to 1.5 × 10 ¹⁵ / cm ² and the acceleration voltage is set to 80 keV. As an impurity element imparting n-type, an element belonging to Group 15, typically phosphorus (P) or arsenic (As), is used here, but phosphorus (P) is used. In this case, the conductive layers 417 to 421 serve as a mask for the impurity element imparting n-type, and the first high-concentration impurity regions 306 to 310 are formed in a self-aligning manner. An impurity element imparting n-type conductivity is added to the first high-concentration impurity regions 306 to 310 in a concentration range of 1 × 10 ²⁰ to 1 × 10 ²¹ atoms / cm ³ .

Next, a second etching process is performed without removing the resist mask. Here, CF ₄ , Cl _2, and O ₂ are used as the etching gas, and the W film is selectively etched. At this time, second conductive layers 428b to 433b are formed by a second etching process. On the other hand, the first conductive layers 417a to 422a are hardly etched, and the second shape conductive layers 428 to 433 are formed.

Next, a second doping process is performed as shown in FIG. 8C without removing the resist mask. In this case, an impurity element imparting n-type conductivity is introduced at a high acceleration voltage of 70 to 120 keV with a lower dose than in the first doping treatment. In this embodiment, the dose is set to 1.5 × 10 ¹⁴ / cm 2, the acceleration voltage is set to 90 keV, and a new semiconductor layer inside the first high-concentration impurity regions 306 to 310 formed in FIG. An impurity region is formed. The second doping process uses the second shape conductive layers 428 to 433 as a mask, and an impurity element is also introduced into the semiconductor layer below the second conductive layers 428 b to 433 b to newly add a second high concentration impurity. Regions 423a to 427a and low concentration impurity regions 423b to 427b are formed.

Next, after removing the resist mask, new resist masks 434a and 434b are formed, and a third etching process is performed as shown in FIG. 9A. SF ₆ and Cl ₂ are used as etching gases, the gas flow rates are 50 sccm and 10 scan, respectively, and 500 W RF (13.56 MHz) power is applied to the coil-type electrode at a pressure of 1.3 Pa to generate plasma. The etching process is performed for about 30 seconds. 10 W of RF (13.56 MHz) power is applied to the substrate side (material stage), and a negative self-bias voltage is substantially applied. Thus, the third etching process is performed to etch the TaN film of the p-channel TFT and the TFT (pixel TFT) in the pixel portion, thereby forming third shape conductive layers 435 to 438.

  Next, after removing the resist mask, the gate insulating film 416 is selectively removed by using the second shape conductive layers 428 and 430 and the second shape conductive layers 435 to 438 as masks. 439 to 444 are formed. (Fig. 9 (B))

Next, new resist masks 445a to 445c are formed, and a third doping process is performed. By this third doping treatment, impurity regions 446 and 447 in which an impurity element imparting a conductivity type opposite to the one conductivity type is added to the semiconductor layer that becomes the active layer of the p-channel TFT. The second conductive layers 435a and 438a are used as masks against the impurity element, and an impurity element imparting p-type is added to form an impurity region in a self-aligning manner. In this embodiment, the impurity regions 446 and 447 are formed by ion doping using diborane (B ₂ H ₆ ). (FIG. 9C) In the third doping process, the semiconductor layer forming the n-channel TFT is covered with masks 445a to 445c made of resist. In the first doping process and the second doping process, phosphorus is added to the impurity regions 446 and 447 at different concentrations, respectively, and the concentration of the impurity element imparting p-type in each of the regions is 2 ×. By performing the doping treatment so as to be 10 ^{20 to} 2 × 10 ²¹ atoms / cm ³ , no problem arises because it functions as the source region and drain region of the p-channel TFT. In this embodiment, since a part of the semiconductor layer serving as an active layer of the p-channel TFT is exposed, there is an advantage that an impurity element (boron) can be easily added.

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

  Next, the resist masks 445a to 445c are removed, and a first interlayer insulating film 461 is formed. The first interlayer insulating film 461 is formed of an insulating film containing silicon with a thickness of 100 to 200 nm by using a plasma CVD method or a sputtering method. In this embodiment, a silicon oxynitride film with a thickness of 150 nm is formed by a plasma CVD method. Needless to say, the first interlayer insulating film 461 is not limited to the silicon oxynitride film, and another insulating film containing silicon may be used as a single layer or a stacked structure.

  Next, as shown in FIG. 10A, a step of activating the impurity element added to each semiconductor layer is performed. This activation step is performed by a thermal annealing method using a furnace annealing furnace. As the thermal annealing method, it may be performed at 400 to 700 ° C., typically 500 to 550 ° C. in a nitrogen atmosphere having an oxygen concentration of 1 ppm or less, preferably 0.1 ppm or less. The activation treatment was performed by heat treatment. In addition to the thermal annealing method, a laser annealing method or a rapid thermal annealing method (RTA method) can be applied. For the laser annealing method, the method disclosed in the present invention may be used.

  Note that in this embodiment, simultaneously with the activation treatment, the impurity regions 423a, 425a, 426a, 446a, and 447a in which nickel used as a catalyst in the crystallization contains high-concentration phosphorus are crystallized. Therefore, the nickel is gettered in the impurity region, and the concentration of nickel in the semiconductor layer mainly serving as a channel formation region is reduced. A TFT having a channel formation region manufactured in this manner has a low off-current value and good crystallinity, so that high field-effect mobility can be obtained and good characteristics can be achieved.

  In addition, an activation process may be performed before forming the first interlayer insulating film. However, when the wiring material used is weak against heat, it is activated after an interlayer insulating film (insulating film containing silicon as a main component, for example, a silicon nitride film) is formed to protect the wiring and the like as in this embodiment. It is preferable to perform the conversion process.

  Further, a step of hydrogenating the semiconductor layer is performed by performing heat treatment at 300 to 550 ° C. for 1 to 12 hours in an atmosphere containing 3 to 100% hydrogen. In this embodiment, heat treatment was performed at 410 ° C. for 1 hour in a nitrogen atmosphere containing about 3% hydrogen. This step is a step of terminating dangling bonds in the semiconductor layer with hydrogen contained in the interlayer insulating film. As another means of hydrogenation, plasma hydrogenation (using hydrogen excited by plasma) may be performed.

  In the case where a laser annealing method is used as the activation treatment, it is desirable to irradiate a laser beam such as an excimer laser or a YAG laser before performing the hydrogenation treatment.

  Next, a second interlayer insulating film 462 made of an inorganic insulating film material or an organic insulating material is formed over the first interlayer insulating film 461. In this embodiment, an acrylic resin film having a thickness of 1.6 μm is formed, but a film having a viscosity of 10 to 1000 cp, preferably 40 to 200 cp, and having a surface with unevenness is used.

  In this embodiment, in order to prevent specular reflection, the surface of the pixel electrode is formed uneven by forming a second interlayer insulating film having an uneven surface. In addition, a convex portion may be formed in a region below the pixel electrode in order to make the surface of the pixel electrode uneven to achieve light scattering. In that case, since the convex portion can be formed using the same photomask as that of the TFT, the convex portion can be formed without increasing the number of steps. In addition, this convex part should just be suitably provided on the board | substrate of pixel part area | regions other than wiring and a TFT part. Thus, irregularities are formed on the surface of the pixel electrode along the irregularities formed on the surface of the insulating film covering the convex portions.

  Alternatively, a film whose surface is planarized may be used as the second interlayer insulating film 462. In that case, after forming the pixel electrode, adding a step such as a known sandblasting method or etching method to make the surface uneven, prevent specular reflection, and increase the whiteness by scattering the reflected light Is preferred.

  In the driver circuit 506, wirings 463 to 467 that are electrically connected to the impurity regions are formed. Note that these wirings are formed by patterning a laminated film of a Ti film having a thickness of 50 nm and an alloy film (alloy film of Al and Ti) having a thickness of 500 nm.

  In the pixel portion 507, a pixel electrode 470, a gate wiring 469, and a connection electrode 468 are formed. (FIG. 10B) With this connection electrode 468, the source wiring (stack of 443b and 449) is electrically connected to the pixel TFT. In addition, the gate wiring 469 is electrically connected to the gate electrode of the pixel TFT. In addition, the pixel electrode 470 is electrically connected to the drain region 442 of the pixel TFT and further electrically connected to the semiconductor layer 458 functioning as one electrode forming a storage capacitor. The pixel electrode 471 is preferably made of a highly reflective material such as a film mainly composed of Al or Ag, or a laminated film thereof.

  As described above, a CMOS circuit including an n-channel TFT 501 and a p-channel TFT 502, a driver circuit 506 having an n-channel TFT 503, and a pixel portion 507 having a pixel TFT 504 and a storage capacitor 505 are formed over the same substrate. can do. Thus, the active matrix substrate is completed.

  The n-channel TFT 501 of the driver circuit 506 includes a channel formation region 423c, a low-concentration impurity region 423b (GOLD region) that overlaps with the first conductive layer 428a which forms part of the gate electrode, and a high function as a source region or a drain region. A concentration impurity region 423a is provided. The p-channel TFT 502 which is connected to the n-channel TFT 501 and the electrode 466 to form a CMOS circuit functions as a channel formation region 446d, impurity regions 446b and 446c formed outside the gate electrode, and a source region or a drain region. A high concentration impurity region 446a is provided. In addition, the n-channel TFT 503 includes a channel formation region 425c, a low-concentration impurity region 425b (GOLD region) that overlaps with the first conductive layer 430a that forms part of the gate electrode, and a high-concentration function as a source region or a drain region. An impurity region 425a is provided.

  The pixel TFT 504 in the pixel portion includes a channel formation region 426c, a low concentration impurity region 426b (LDD region) formed outside the gate electrode, and a high concentration impurity region 426a functioning as a source region or a drain region. In addition, an impurity element imparting p-type conductivity is added to each of the semiconductor layers 447a and 447b functioning as one electrode of the storage capacitor 505. The storage capacitor 505 is formed using an electrode (a stack of 438a and 438b) and semiconductor layers 447a to 447c using the insulating film 444 as a dielectric.

In the pixel structure of this embodiment, the end of the pixel electrode overlaps with the source wiring so that the gap between the pixel electrodes is shielded from light without using a black matrix.

  FIG. 11 is a top view of the pixel portion of the active matrix substrate manufactured in this embodiment. In addition, the same code | symbol is used for the part corresponding to FIGS. A chain line A-A ′ in FIG. 10 corresponds to a cross-sectional view taken along the chain line A-A ′ in FIG. 11. Further, a chain line B-B ′ in FIG. 10 corresponds to a cross-sectional view taken along the chain line B-B ′ in FIG. 11.

  Note that this embodiment can be freely combined with any one of Embodiments 1 to 3.

(Example 5)
In this example, an example in which an EL (electroluminescence) display device is manufactured as an example of a light-emitting device using the present invention will be described.

  In this specification, the light emitting device is a general term for a display panel in which a light emitting element formed on a substrate is sealed between the substrate and a cover material, and a display module in which an IC is mounted on the display panel. is there. Note that the light-emitting element includes a layer (light-emitting layer) containing an organic compound from which luminescence (Electro Luminescence) generated by applying an electric field is obtained, an anode layer, and a cathode layer. In addition, luminescence in an organic compound includes light emission (fluorescence) when returning from a singlet excited state to a ground state and light emission (phosphorescence) when returning from a triplet excited state to a ground state, one of these, Or both luminescence is included.

  FIG. 13 is a cross-sectional view of an EL display device of the present invention. In FIG. 13, a switching TFT 603 provided over a substrate 700 is formed using the n-channel TFT 503 in FIG. Therefore, the description of the n-channel TFT 503 may be referred to for the description of the structure.

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

  A driver circuit provided over the substrate 700 is formed using the CMOS circuit of FIG. Therefore, for the description of the structure, the description of the n-channel TFT 501 and the p-channel TFT 502 may be referred to. In this embodiment, a single gate structure is used, but a double gate structure or a triple gate structure may be used.

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

  Note that the current control TFT 604 is formed using the p-channel TFT 502 of FIG. Accordingly, the description of the p-channel TFT 502 may be referred to for the description of the structure. In this embodiment, a single gate structure is used, but a double gate structure or a triple gate structure may be used.

  A wiring 706 is a source wiring (corresponding to a current supply line) of the current control TFT, and 707 is an electrode that is electrically connected to the pixel electrode 710 by being overlaid on the pixel electrode 710 of the current control TFT.

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

  After the wirings 701 to 707 are formed, a bank 712 is formed as shown in FIG. The bank 712 may be formed by patterning an insulating film or organic resin film containing silicon of 100 to 400 nm.

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

An EL layer 713 is formed over the pixel electrode 710. Although only one pixel is shown in FIG. 13, in this embodiment, EL layers corresponding to R (red), G (green), and B (blue) colors are separately created. In this embodiment, a low molecular organic EL material is formed by a vapor deposition method. Specifically, a laminated structure in which a copper phthalocyanine (CuPc) film having a thickness of 20 nm is provided as a hole injection layer and a tris-8-quinolinolato aluminum complex (Alq ₃ ) film having a thickness of 70 nm is provided thereon as a light emitting layer. It is said. The emission color can be controlled by adding a fluorescent dye such as quinacridone, perylene, or DCM1 to Alq ₃ .

  However, the above example is an example of an organic EL material that can be used as an EL layer, and is not necessarily limited to this. An EL layer (a layer for emitting light and moving carriers therefor) may be formed by freely combining a light-emitting layer, a charge transport layer, or a charge injection layer. For example, in this embodiment, an example in which a low molecular weight organic EL material is used as an EL layer is shown, but a high molecular weight organic EL material may be used. It is also possible to use an inorganic material such as silicon carbide for the charge transport layer or the charge injection layer. As these organic EL materials and inorganic materials, known materials can be used.

  Next, a cathode 714 made of a conductive film is provided over the EL layer 713. In this embodiment, an alloy film of aluminum and lithium is used as the conductive film. Of course, a known MgAg film (magnesium and silver alloy film) may be used. As the cathode material, a conductive film made of an element belonging to Group 1 or Group 2 of the periodic table or a conductive film added with these elements may be used.

  When the cathode 714 is formed, the EL element 715 is completed. Note that the EL element 715 here refers to a capacitor formed by a pixel electrode (anode) 710, an EL layer 713, and a cathode 714.

  It is effective to provide a passivation film 716 so as to completely cover the EL element 715. As the passivation film 716, an insulating film including a carbon film, a silicon nitride film, or a silicon nitride oxide film is used, and the insulating film is used as a single layer or a combination thereof.

At this time, it is preferable to use a film with good coverage as the passivation film, and it is effective to use a carbon film, particularly a DLC (diamond-like carbon) film. Since the DLC film can be formed in a temperature range from room temperature to 100 ° C., it can be easily formed over the EL layer 713 having low heat resistance. In addition, the DLC film has a high blocking effect against oxygen and can suppress oxidation of the EL layer 713. Therefore, the problem that the EL layer 713 is oxidized during the subsequent sealing process can be prevented.

  Further, a sealing material 717 is provided over the passivation film 716 and a cover material 718 is attached thereto. As the sealing material 717, an ultraviolet curable resin may be used, and it is effective to provide a substance having a hygroscopic effect or a substance having an antioxidant effect inside. In this embodiment, the cover material 718 is formed by forming a carbon film (preferably a diamond-like carbon film) on both surfaces of a glass substrate, a quartz substrate, or a plastic substrate (including a plastic film).

  Thus, an EL display device having a structure as shown in FIG. 13 is completed. Note that it is effective to continuously process the steps from the formation of the bank 712 to the formation of the passivation film 716 using a multi-chamber type (or in-line type) film formation apparatus without releasing to the atmosphere. . Further, it is possible to continuously process the process up to the step of bonding the cover material 718 without releasing to the atmosphere.

  Thus, the n-channel TFTs 601 and 602, the switching TFT (n-channel TFT) 603, and the current control TFT (n-channel TFT) 604 are formed on the insulator 501 having the plastic substrate as a base. The number of masks required in the manufacturing process so far is smaller than that of a general active matrix EL display device.

  That is, the TFT manufacturing process is greatly simplified, and the yield can be improved and the manufacturing cost can be reduced.

  Furthermore, as described with reference to FIGS. 13A and 13B, an n-channel TFT which is resistant to deterioration due to the hot carrier effect can be formed by providing an impurity region overlapping with the gate electrode through an insulating film. Therefore, a highly reliable EL display device can be realized.

  Further, in this embodiment, only the configuration of the pixel portion and the drive circuit is shown. However, according to the manufacturing process of this embodiment, other logic circuits such as a signal dividing circuit, a D / A converter, an operational amplifier, and a γ correction circuit are provided. Can be formed on the same insulator, and a memory and a microprocessor can also be formed.

  Further, the EL light-emitting device of this example after performing the sealing (or sealing) process for protecting the EL element will be described with reference to FIG. In addition, the code | symbol used in FIG. 13 is quoted as needed.

  FIG. 14A is a top view illustrating a state where the EL element is sealed, and FIG. 14B is a cross-sectional view taken along line C-C ′ in FIG. Reference numeral 801 indicated by a dotted line denotes a source side driver circuit, 806 denotes a pixel portion, and 807 denotes a gate side driver circuit. Reference numeral 901 denotes a cover material, reference numeral 902 denotes a first sealing material, reference numeral 903 denotes a second sealing material, and a sealing material 907 is provided on the inner side surrounded by the first sealing material 902.

  Reference numeral 904 denotes a wiring for transmitting signals input to the source side driver circuit 801 and the gate side driver circuit 807, and receives a video signal and a clock signal from an FPC (flexible printed circuit) 905 serving as an external input terminal. Although only the FPC is shown here, a printed wiring board (PWB) may be attached to the FPC. The EL display device in this specification includes not only the EL display device main body but also a state in which an FPC or PWB is attached thereto.

  Next, a cross-sectional structure is described with reference to FIG. A pixel portion 806 and a gate side driver circuit 807 are formed above the substrate 700, and the pixel portion 806 is formed by a plurality of pixels including a current control TFT 604 and a pixel electrode 710 electrically connected to a drain thereof. . The gate side driver circuit 807 is formed using a CMOS circuit (see FIG. 15) in which an n-channel TFT 601 and a p-channel TFT 602 are combined.

  The pixel electrode 710 functions as an anode of the EL element. A bank 712 is formed at both ends of the pixel electrode 710, and an EL layer 713 and a cathode 714 of the EL element are formed on the pixel electrode 710.

  The cathode 714 also functions as a wiring common to all pixels, and is electrically connected to the FPC 905 via the connection wiring 904. Further, all elements included in the pixel portion 806 and the gate side driver circuit 807 are covered with a cathode 714 and a passivation film 567.

  Further, a cover material 901 is bonded to the first seal material 902. Note that a spacer made of a resin film may be provided in order to secure a gap between the cover material 901 and the EL element. A sealing material 907 is filled inside the first sealing material 902. Note that an epoxy-based resin is preferably used as the first sealing material 902 and the sealing material 907. The first sealing material 902 is desirably a material that does not transmit moisture and oxygen as much as possible. Further, a substance having a hygroscopic effect or a substance having an antioxidant effect may be contained in the sealing material 907.

  The sealing material 907 provided so as to cover the EL element also functions as an adhesive for bonding the cover material 901. In this embodiment, FRP (Fiberglass-Reinforced Plastics), PVF (polyvinyl fluoride), Mylar, polyester, or acrylic can be used as the material of the plastic substrate 901a constituting the cover material 901.

  In addition, after the cover material 901 is bonded using the sealing material 907, the second sealing material 903 is provided so as to cover the side surface (exposed surface) of the sealing material 907. The second sealing material 903 can use the same material as the first sealing material 902.

  By encapsulating the EL element in the sealing material 907 with the above structure, the EL element can be completely shut off from the outside, and a substance that promotes deterioration due to oxidation of the EL layer such as moisture or oxygen enters from the outside. Can be prevented. Therefore, an EL display device with high reliability can be obtained.

  The semiconductor film in the light-emitting device manufactured as described above is sufficiently crystallized by a laser beam in which interference is reduced at or near the irradiated surface and the uniformity of energy distribution is significantly improved. . Therefore, sufficient operating characteristics and reliability can be realized also in the light emitting device. And such a light-emitting device can be used as a display part of various electronic devices.

  Note that this embodiment can be freely combined with any one of Embodiments 1 to 3.

(Example 6)
In this embodiment, a process of manufacturing a reflective liquid crystal display device from the active matrix substrate manufactured in Embodiment 4 will be described below. FIG. 12 is used for the description.

  First, an active matrix substrate in the state of FIG. 10B is obtained according to Embodiment 4, and then an alignment film 471 is formed on at least the pixel electrode 470 on the active matrix substrate of FIG. . In this embodiment, before the alignment film 471 is formed, a columnar spacer 480 for maintaining a substrate interval is formed at a desired position by patterning an organic resin film such as an acrylic resin film. Further, instead of the columnar spacers, spherical spacers may be scattered over the entire surface of the substrate.

  Next, a counter substrate 472 is prepared. Next, colored layers 473 and 474 and a planarization film 475 are formed over the counter substrate 472. The red colored layer 473 and the blue colored layer 474 are overlapped to form a light shielding portion. Further, the light shielding portion may be formed by partially overlapping the red colored layer and the green colored layer.

  In this example, the substrate shown in Example 4 is used. Therefore, in FIG. 11 showing a top view of the pixel portion of Embodiment 4, at least the gap between the gate wiring 469 and the pixel electrode 470, the gap between the gate wiring 469 and the connection electrode 468, and the gap between the connection electrode 468 and the pixel electrode 470 are provided. It is necessary to shield the light. In this example, the respective colored layers were arranged so that the light-shielding portions formed by the lamination of the colored layers overlapped at the positions where light shielding should be performed, and the counter substrate was bonded.

  As described above, the number of steps can be reduced by shielding the gap between the pixels with the light shielding portion formed by the lamination of the colored layers without forming a light shielding layer such as a black mask.

  Next, a counter electrode 476 made of a transparent conductive film was formed over the planarization film 475 in at least the pixel portion, an alignment film 477 was formed over the entire surface of the counter substrate, and a rubbing process was performed.

  Then, the active matrix substrate on which the pixel portion and the driver circuit are formed and the counter substrate are attached to each other with a sealant 478. Filler is mixed in the sealing material 478, and two substrates are bonded to each other with a uniform interval by the filler and the columnar spacer. Thereafter, a liquid crystal material 479 is injected between both substrates and completely sealed with a sealant (not shown). A known liquid crystal material may be used for the liquid crystal material 479. In this way, the reflection type liquid crystal display device shown in FIG. 12 is completed. If necessary, the active matrix substrate or the counter substrate is divided into a desired shape. Further, a polarizing plate (not shown) was attached only to the counter substrate. And FPC was affixed using the well-known technique.

  The semiconductor film in the liquid crystal display device manufactured as described above is sufficiently crystallized by a laser beam in which interference is reduced at or near the irradiated surface and the uniformity of energy distribution is remarkably improved. Yes. Therefore, sufficient operating characteristics and reliability can be realized also in the liquid crystal display device. And such a liquid crystal display device can be used as a display part of various electronic devices.

  Note that this embodiment can be freely combined with any one of Embodiments 1 to 4.

(Example 7)
The CMOS circuit and the pixel portion formed by implementing the present invention can be used for various electro-optical devices (active matrix liquid crystal display, active matrix EC display, active matrix EL display). That is, the present invention can be applied to all electronic devices in which these electro-optical devices are incorporated in a display unit.

  Such electronic devices include video cameras, digital cameras, projectors (rear type or front type), head mounted displays (goggles type displays), car navigation systems, car stereos, personal computers, personal digital assistants (mobile computers, mobile phones) Or an electronic book). Examples of these are shown in FIGS. 15, 16 and 17.

  FIG. 15A shows a personal computer, which includes a main body 3001, an image input portion 3002, a display portion 3003, a keyboard 3004, and the like. The present invention can be applied to the image input unit 3002, the display unit 3003, and other signal control circuits.

  FIG. 15B illustrates a video camera, which includes a main body 3101, a display portion 3102, an audio input portion 3103, operation switches 3104, a battery 3105, an image receiving portion 3106, and the like. The present invention can be applied to the display portion 3102 and other signal control circuits.

  FIG. 15C illustrates a mobile computer, which includes a main body 3201, a camera portion 3202, an image receiving portion 3203, operation switches 3204, a display portion 3205, and the like. The present invention can be applied to the display portion 3205 and other signal control circuits.

  FIG. 15D illustrates a goggle-type display, which includes a main body 3301, a display portion 3302, an arm portion 3303, and the like. The present invention can be applied to the display portion 3302 and other signal control circuits.

  FIG. 15E shows a player using a recording medium (hereinafter referred to as a recording medium) on which a program is recorded, and includes a main body 3401, a display portion 3402, a speaker portion 3403, a recording medium 3404, an operation switch 3405, and the like. This player uses a DVD (Digital Versatile Disc), CD, or the like as a recording medium, and can perform music appreciation, movie appreciation, games, and the Internet. The present invention can be applied to the display portion 3402 and other signal control circuits.

  FIG. 15F illustrates a digital camera, which includes a main body 3501, a display portion 3502, an eyepiece portion 3503, an operation switch 3504, an image receiving portion (not shown), and the like. The present invention can be applied to the display portion 3502 and other signal control circuits.

  FIG. 16A illustrates a front type projector, which includes a projection device 3601, a screen 3602, and the like. The present invention can be applied to a liquid crystal display device 3808 constituting a part of the projection device 3601 and other signal control circuits.

  FIG. 16B shows a rear projector, which includes a main body 3701, a projection device 3702, a mirror 3703, a screen 3704, and the like. The present invention can be applied to the liquid crystal display device 3808 constituting a part of the projection device 3702 and other signal control circuits.

  Note that FIG. 16C is a diagram illustrating an example of the structure of the projection devices 3601 and 3702 in FIGS. 16A and 16B. The projection devices 3601 and 3702 include a light source optical system 3801, mirrors 3802 and 3804 to 3806, a dichroic mirror 3803, a prism 3807, a liquid crystal display device 3808, a phase difference plate 3809, and a projection optical system 3810. The projection optical system 3810 is composed of an optical system including a projection lens. Although the present embodiment shows a three-plate type example, it is not particularly limited, and for example, a single-plate type may be used. Further, the practitioner may appropriately provide an optical system such as an optical lens, a film having a polarization function, a film for adjusting a phase difference, an IR film, or the like in the optical path indicated by an arrow in FIG. Good.

  FIG. 16D illustrates an example of the structure of the light source optical system 3801 in FIG. In this embodiment, the light source optical system 3801 includes a reflector 3811, a light source 3812, lens arrays 3813 and 3814, a polarization conversion element 3815, and a condenser lens 3816. Note that the light source optical system illustrated in FIG. 16D is an example and is not particularly limited. For example, the practitioner may appropriately provide an optical system such as an optical lens, a film having a polarization function, a film for adjusting a phase difference, or an IR film in the light source optical system.

  However, the projector shown in FIG. 16 shows a case in which a transmissive electro-optical device is used, and an application example in a reflective electro-optical device is not shown.

  FIG. 17A illustrates a mobile phone, which includes a main body 3901, an audio output portion 3902, an audio input portion 3903, a display portion 3904, operation switches 3905, an antenna 3906, and the like. The present invention can be applied to the audio output unit 3902, the audio input unit 3903, the display unit 3904, and other signal control circuits.

  FIG. 17B illustrates a portable book (electronic book), which includes a main body 4001, display portions 4002 and 4003, a storage medium 4004, operation switches 4005, an antenna 4006, and the like. The present invention can be applied to the display portions 4002 and 4003 and other signal circuits.

  FIG. 17C illustrates a display, which includes a main body 4101, a support base 4102, a display portion 4103, and the like. The present invention can be applied to the display portion 4103. The display of the present invention is particularly advantageous when the screen is enlarged, and is advantageous for displays having a diagonal of 10 inches or more (particularly 30 inches or more).

  As described above, the application range of the present invention is extremely wide and can be applied to electronic devices in various fields. Further, the electronic apparatus of the present embodiment can be realized by using a configuration including any combination of Embodiments 1 to 5 or 6.

Effect of the invention

  In the energy distribution of a laser beam having coherence, the effect of reducing the coherence of the laser beam and significantly improving the uniformity of the energy distribution of the laser beam simply by applying the present invention to an optical system that has been conventionally used. There is. When the invention disclosed in this specification is combined with a solid-state laser typified by a highly coherent YAG laser and used in a semiconductor film crystallization process, significant cost reduction can be expected. In addition, a TFT is manufactured using the semiconductor film thus obtained, and in an electro-optical device and a semiconductor device typified by an active matrix liquid crystal display device manufactured using the TFT, sufficient operating characteristics and Reliability can be realized.

The figure which shows the example of the laser irradiation apparatus which this invention discloses. The figure which shows the example of the conventional laser irradiation apparatus. The figure which shows the mode of 2 light wave interference by a beam with high coherence. The figure which shows the example of the laser irradiation apparatus which this invention discloses. The figure which shows the example of the laser irradiation apparatus for mass production. The figure which shows the energy distribution of the shape produced by the spherical aberration of a cylindrical lens. Sectional drawing which shows the manufacturing process of TFT of a pixel TFT and a driver circuit. Sectional drawing which shows the manufacturing process of TFT of a pixel TFT and a driver circuit. Sectional drawing which shows the manufacturing process of TFT of a pixel TFT and a driver circuit. Sectional drawing which shows the manufacturing process of TFT of a pixel TFT and a driver circuit. FIG. 6 is a top view illustrating a configuration of a pixel TFT. Sectional drawing which shows the structure of a liquid crystal panel. Sectional drawing which shows the manufacturing process of EL display apparatus. Sectional drawing which shows the manufacturing process of EL display apparatus. FIG. 14 illustrates an example of an electronic device. FIG. 14 illustrates an example of an electronic device. FIG. 14 illustrates an example of an electronic device.

101 Laser oscillator 102 Cylindrical lens array 103 Cylindrical lens array 104 Cylindrical lens 105 Cylindrical lens 105 Cylindrical lens 106 Cylindrical lens 107 Mirror 108 Irradiation surface 109 Stepped quartz plate 110 λ / 2 plate 201 Laser oscillator 202 Cylindrical lens array 203 Cylindrical lens array 204 Cylindrical lens 205 Cylindrical lens 206 Mirror 207 Doublet cylindrical lens 208 Irradiation surface 1401 Laser oscillator 1402 Beam expander 1403 Stepped quartz plate 1404 λ / 2 plate 1405 Cylindrical lens array 1406 Cylindrical lens 1407 Cylindrical lens array 1408 Mirror 1409 Cylindrical lens 1410 Irradiation surface 1500 Laser oscillator 1501 Load / unload chamber 1502 Transfer chamber 1503 Robot arm 1504 Alignment chamber 1505 Preheating chamber 1506 Gate valve 1507 Laser irradiation chamber 1508 Cooling chamber 1509 Optical system 1510 Quartz window 1511 Vacuum pump 1512 Gas cylinder 1513 Moving mechanism

Claims (14)

A laser irradiation apparatus for forming a linear beam having a uniform energy distribution at or near an irradiation surface,
A laser oscillator for emitting a laser beam;
In a first direction perpendicular to the direction of travel of the laser beam,
A stepped quartz plate that converts the laser beam into laser beams having different optical path lengths;
A first cylindrical lens array for dividing the plurality of laser beams having different optical path lengths;
First combining means for making the plurality of laser beams one at or near the irradiated surface and uniformizing the energy distribution in the longitudinal direction of the linear beam;
In a second direction perpendicular to the direction of travel of the laser beam and perpendicular to the first direction,
A λ / 2 plate for converting the laser beam into laser beams having different polarization directions;
A second cylindrical lens array for dividing the laser beams having different polarization directions into two laser beams;
Second combining means for making the two laser beams one at or near the irradiation surface and uniformizing the energy distribution in the short direction of the linear beam;
Have
The laser irradiation apparatus, wherein the stepped quartz plate, the λ / 2 plate, the second cylindrical lens array, and the first cylindrical array are arranged in this order with respect to the traveling direction of the laser beam. .
In claim 1,
The laser irradiation apparatus, wherein the number of steps of the stepped quartz plate is one less than the number of the plurality of laser beams.
In claim 1 or claim 2,
A beam expander that converts the laser beam output from the laser oscillator into an elliptical laser beam;
The λ / 2 plate is rectangular, and is arranged so that one side of the rectangle and the diameter of the elliptical laser beam coincide with each other.
In any one of Claim 1 thru | or 3,
The laser irradiation apparatus, wherein the first combining unit includes a cylindrical lens having an F value of 20 or more.
In any one of Claims 1 thru | or 4,
The laser irradiation apparatus characterized in that the two laser beams have polarization directions perpendicular to each other.
In any one of Claims 1 thru | or 4,
The laser irradiation apparatus, wherein the laser beams having different polarization directions are linearly polarized light or circularly polarized laser beam.
In any one of Claims 1 thru | or 6,
The laser irradiation apparatus, wherein the second cylindrical lens array includes a plurality of cylindrical lenses having at least an F value of 20 or more.
In any one of Claims 1 thru | or 7,
2. The laser irradiation apparatus according to claim 1, wherein the laser beam is a laser beam oscillated from one kind or plural kinds selected from a YAG laser, a YVO ₄ laser, and a YLF laser.
In a method for manufacturing a semiconductor device in which a TFT is provided over a substrate,
In a first direction Ru perpendicular der in the traveling direction of the les Zabimu, by entering the laser beam stepwise quartz plate, and the laser beam having different optical path lengths from each other,
In a second direction perpendicular to the traveling direction of the laser beam and perpendicular to the first direction, the laser beam is incident on the λ / 2 plate to obtain laser beams having different polarization directions,
In the second direction, the laser beams having different polarization directions are incident on the first cylindrical lens array to be split into two laser beams having different polarization directions;
In the first direction, the laser beams having different optical path lengths are incident on the second cylindrical lens array to be split into a plurality of laser beams having different optical path lengths,
The two laser beams are combined into one at or near the irradiated surface, the plurality of laser beams are combined into one at or near the irradiated surface, and the direction parallel to the second direction is the short direction. And forming a linear beam in which the direction parallel to the first direction is the longitudinal direction,
A method for manufacturing a semiconductor device, wherein the non-single crystal semiconductor film is irradiated while moving the linear beam relatively.
In claim 9,
A method of manufacturing a semiconductor device, wherein the stepped quartz plate is a quartz plate having one step number less than the number of the plurality of laser beams.
In claim 9 or claim 10,
Before the laser beam is incident on the stepped quartz plate, an elliptical laser beam is incident on a beam expander,
The method of manufacturing a semiconductor device, wherein the λ / 2 plate has a rectangular shape and is arranged so that one side of the rectangular shape coincides with the diameter of the elliptical laser beam.
In any one of Claims 9 to 11,
A method for manufacturing a semiconductor device, wherein a plurality of cylindrical lenses having at least an F value of 20 or more are used as the second cylindrical lens array.
In any one of Claims 9-12,
A method for manufacturing a semiconductor device, wherein a cylindrical lens having at least an F value of 20 or more is used as the first cylindrical lens array .
14. The semiconductor according to claim 9, wherein a laser beam oscillated from one or a plurality of types selected from a YAG laser, a YVO ₄ laser, and a YLF laser is used as the laser beam. Device fabrication method.

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