JP2006339630A - Laser radiation apparatus and laser radiation method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To radiate a laser beam with uniform intensity distribution without causing interference fringes of a laser to appear on an irradiation surface. <P>SOLUTION: A laser beam emitted from a laser oscillator passes through a diffractive-optical element so as to have uniform intensity distribution. The beam emitted from the diffractive-optical element then passes through a slit so that low-intensity end portions in the major axis direction of the beam are cut off. The beam passes through a projector lens and a condensing lens so as to project an image of the slit onto an irradiation surface. The projector lens is positioned so that the slit and the irradiation surface are conjugated. This method prevents diffraction by the slit and irradiates the irradiation surface with the laser beam with uniform intensity. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a laser irradiation apparatus (laser and an optical system for guiding laser light output from the laser to an irradiated body) for uniformly and efficiently performing annealing as performed on a semiconductor material or the like. And a laser irradiation method. In addition, the present invention relates to a semiconductor device manufactured including a process of performing processing using the laser processing apparatus and the laser processing method, and a manufacturing method thereof.

  In recent years, a technique for manufacturing a thin film transistor (hereinafter referred to as TFT) on a substrate has greatly advanced, and application development to an active matrix display device has been advanced. In particular, a TFT using a polycrystalline semiconductor film has higher electrolytic effect mobility (also referred to as mobility) than a conventional TFT using an amorphous semiconductor film, and thus can operate at high speed. For this reason, it is used to control a pixel, which has been conventionally performed by a driving circuit provided outside the substrate, by a driving circuit formed on the same substrate as the pixel.

  By the way, as a substrate used for a semiconductor device, a glass substrate is considered to be more promising than a quartz substrate or a single crystal semiconductor substrate in terms of cost. However, the glass substrate is inferior in heat resistance and easily deforms thermally. Therefore, when the semiconductor film is crystallized to form a TFT using a polycrystalline semiconductor film on a glass substrate, laser annealing is often used to avoid thermal deformation of the glass substrate.

  The characteristics of laser annealing are that the processing time can be greatly reduced compared to annealing methods using radiation heating or conduction heating, and the semiconductor substrate or semiconductor film on the substrate is selectively and locally heated. For example, there is almost no thermal damage to the substrate. The laser annealing method here refers to a technique for recrystallizing a damaged layer or an amorphous layer formed on a semiconductor substrate or semiconductor film, or a technique for crystallizing a non-single-crystal semiconductor film formed on a substrate. pointing. It also includes techniques applied to planarization and surface modification of semiconductor substrates or semiconductor films.

Laser oscillators used for laser annealing are roughly classified into two types, pulse oscillation and continuous oscillation, depending on the oscillation method. In recent years, in crystallization of a semiconductor film, it is more preferable to use a continuous oscillation laser oscillator such as an Ar laser or a YVO ₄ laser than a pulse oscillation laser oscillator such as an excimer laser. It has been found that the particle size of As the crystal grain size in the semiconductor film increases, the number of grain boundaries entering the TFT channel region formed using this semiconductor film decreases. Therefore, the mobility becomes high and it can be used for the development of a higher performance device. Therefore, continuous wave laser oscillators are in the spotlight.

  Usually, a laser beam spot used for laser annealing of a semiconductor film is linear, and laser annealing is performed by scanning a laser beam spot shaped into a linear shape on the semiconductor film. By linearly shaping the laser beam spot, the area that can be laser annealed at a time can be increased. Note that in this specification, laser beams whose shapes on the irradiation surface are linear and rectangular are referred to as a linear beam and a rectangular beam, respectively. Note that “linear” here does not mean “line” in a strict sense, but means a rectangle with a large aspect ratio (for example, an aspect ratio of 10 or more (preferably 100 to 10,000)). To do. Note that the linear shape is used to ensure sufficient strength for annealing the irradiated object, so that sufficient annealing can be performed on the irradiated object even in a rectangular or planar shape. If it is. In the future, laser annealing may be performed using a planar beam.

On the other hand, when crystallizing a silicon film with a thickness of several tens to several hundreds of nanometers normally used in a semiconductor device with a YAG laser or a YVO ₄ laser, a second harmonic having a shorter wavelength than the fundamental wave is used. This is because the second harmonic wave has a larger absorption coefficient of the laser beam with respect to the semiconductor film than the fundamental wave, so that the semiconductor film can be efficiently crystallized. Note that the fundamental wave is rarely used in this process.

  As an example of this process, a CW (continuous oscillation) laser beam having a second harmonic of 10 W and 532 nm is shaped into a linear shape having a major axis direction of 300 μm and a minor axis direction of about 10 μm. Crystallization is performed by scanning the beam spot in the direction and performing laser annealing. The width of the large grain crystal region obtained by one scan is about 200 μm (hereinafter, the region where the large grain crystal is seen is referred to as the large grain region). Therefore, in order to crystallize the entire surface of the substrate by laser annealing, the laser beam scanning position is set in the major axis direction of the beam spot by the width of the large grain crystal region obtained by one scanning of the beam spot. It is necessary to perform laser annealing by shifting.

The applicant of the present invention has already filed an application in which the semiconductor film is irradiated with a linear laser beam on or near the irradiated surface.
Japanese Patent Application Laid-Open No. 2003-257885

  Here, FIG. 25 shows a beam spot 2500, an irradiation trace 2501 in the semiconductor film when the beam spot 2500 is irradiated, and an intensity distribution 2502 in a section along the a-a ′ of the beam spot 2500.

In general, the cross section of a laser beam emitted from a TEM ₀₀ (single transverse mode) continuous oscillation laser oscillator has a Gaussian distribution type intensity distribution indicated by 2502 in FIG. 25 and has a uniform distribution. Not.

  For example, the portion 2500a in the vicinity of the center of the beam spot 2500 can obtain a crystal grain having a large particle size that allows one TFT to be formed on at least one crystal particle (hereinafter referred to as a large crystal particle size). The strength is greater than the threshold value (y). At this time, it is assumed that the portion 2500b in the vicinity of the end portion of the beam spot has a strength higher than the threshold value (x) at which the crystalline region is formed and is lower than the threshold value (y). When the semiconductor film is irradiated with such a beam spot 2500, in the irradiation trace 2501, a region that cannot be partially melted remains in the region 2501b irradiated with the end portion of the beam spot. Therefore, in the region 2501b, only a crystal grain having a relatively small grain size (hereinafter referred to as a microcrystal) is formed, not a crystal grain having a large grain size as formed in the region 2501a irradiated with the central portion of the beam. Will be.

  Even if a semiconductor element is formed in the region where the microcrystal is formed in this way, that is, in the region 2501b near the end of the beam spot, high characteristics cannot be expected. In order to avoid this, a semiconductor element is formed in a portion where a crystal grain having a large grain size is formed, that is, a region 2501a near the center of the beam spot. is there. Therefore, it is required to reduce the ratio of the region where the microcrystal is formed in the entire region irradiated with the laser beam.

  In order to avoid this, there is a method in which the intensity distribution of the laser beam is not a Gaussian shape but a top flat type. By adopting the top flat type, the end portion of the intensity distribution of the laser beam can be made sharp, and the crystalline defect region formed after laser annealing can be reduced.

  In addition, the laser beam has excellent directivity due to the characteristics of the configuration of the laser resonator, and has coherence. However, good coherence is not always an advantage. As shown in FIG. 26, the laser beam emitted from the laser oscillator 2601 reaches the slit 2603 after the intensity distribution is made uniform by the diffractive optical element 2602. The laser beam reaches the irradiation surface 2604 after being diffracted when passing through the slit 2603. Due to interference of diffracted light on the irradiation surface 2604, diffraction fringes having an intensity distribution as shown in 2605 are generated. If the semiconductor film is subjected to laser irradiation treatment in such a state of intensity distribution, it is difficult to uniformly anneal the entire surface of the semiconductor film.

  In order to solve the above problems, the present invention has the following configuration. Note that the laser annealing method referred to here is a technique for crystallizing a damaged region or an amorphous region formed by ion implantation or the like on a semiconductor substrate or semiconductor film, or a semiconductor film that is not a single crystal formed on the substrate (non-crystalline). Crystallization by applying laser irradiation to a non-single crystal semiconductor film after introducing a catalytic element that promotes crystallization such as nickel into a non-single crystal semiconductor film. It refers to the technology that makes it happen.

  Moreover, the technique applied to planarization and surface modification of a semiconductor substrate or a semiconductor film is also included. The term “semiconductor device” as used herein refers to all devices that can function by utilizing semiconductor characteristics, and includes electro-optical devices such as liquid crystal display devices and light-emitting devices, and electronic devices including these electro-optical devices as components. Shall be.

  One of the inventions disclosed in the present invention is to cut off both ends of a laser oscillator, a beam homogenizer that equalizes the intensity distribution of the laser beam emitted from the laser oscillator, and the laser beam emitted from the laser oscillator. A projection lens for projecting the slit image onto the irradiation surface, a condensing lens for condensing the slit image, and means for moving the irradiation surface relative to the laser beam.

  In the present invention, it is possible to pass through a beam homogenizer that operates the phase conjugate mirror to align the phase of the laser beam and uniformizes the intensity distribution of the laser beam.

  In the present invention, the beam homogenizer is a diffractive optical element.

In the present invention, the projection lens is a convex cylindrical lens or a convex spherical lens. The slit opening width is a, the long axis of the laser beam on the irradiation surface is b, the focal length of the projection lens is f, and the exit side surface of the slit (hereinafter referred to as “rear surface”) to the projection lens. Where d _{1 is} the distance from the first principal point to d ₂ and the distance from the second principal point of the projection lens to the irradiation surface is d ₂ , a, b, f, d ₁ , and d ₂ are expressed by the following formula (1). , (2) is preferable.
1 / f = 1 / d ₁ + 1 / d ₂ (1)
d ₁ : d ₂ = a: b (2)

  That is, the projection lens is disposed at a position where the rear surface of the slit and the irradiation surface are in a conjugate relationship. By doing in this way, it can condense so that the image of a slit may be imaged again on the irradiation surface.

  In the present invention, the condensing lens is a convex cylindrical lens or a convex spherical lens.

In the present invention, a continuous wave laser (hereinafter referred to as “CW laser”) or a pulse laser having an oscillation frequency of 10 MHz or more can be used as the laser oscillator. Laser types include single crystal YAG, YVO ₄ , forsterite, YAlO ₃ , GdVO ₄ , polycrystalline YAG, Y ₂ O ₃ , YVO ₄ , YAlO ₃ , GdVO ₄ , or in an optical fiber, or dopant. As a laser, an Ar ion laser, a Ti: sapphire laser, or the like using a crystal added with one or more of Nd, Yb, Cr, Ti, Ho, Er, Tm, and Ta as a medium can be used. These can be oscillated by continuous oscillation, and can be pulse-oscillated at an oscillation frequency of 10 MHz or more by performing Q switch operation or mode synchronization.

  In addition to the CW laser, a pulse laser having a high oscillation frequency can be used for annealing the semiconductor film. Use of a pulse laser having a high oscillation frequency has the following advantages. It is said that the time from when the semiconductor film is irradiated with the laser beam until the semiconductor film is completely solidified is several tens to several hundreds nsec. Therefore, in a pulse laser with a low oscillation frequency, the next pulse is irradiated after the semiconductor film is melted and solidified by the laser. Therefore, after each pulse is irradiated, the crystal grains grow radially in a central symmetry during recrystallization. Since grain boundaries are formed at the boundaries between adjacent crystal grains, irregularities occur on the surface of the semiconductor film.

  When a pulse laser with a high oscillation frequency is used, the semiconductor film is irradiated with the next pulse during the period from when the semiconductor film is melted by the laser to solidification. Therefore, unlike the case of using a pulse laser having a low oscillation frequency, the solid-liquid interface can be continuously moved in the semiconductor film. Accordingly, a semiconductor film having crystal grains continuously grown in the laser scanning direction can be formed.

  Further, one of the characteristics of a pulse oscillation laser is that the peak output per pulse can be increased by increasing the oscillation frequency. Therefore, even if the average output is relatively low, the conversion efficiency of the laser beam to the second harmonic can be significantly increased. As a result, it is possible to easily obtain high-output harmonics, so that productivity can be greatly improved.

  When a laser oscillator using a single crystal as a medium is used, the laser beam has a length in the major axis direction of 0.5 to 1 mm and a length in the minor axis direction of 20 μm or less, preferably 10 μm or less on the irradiated surface. To shape. Further, scanning is performed in the minor axis direction of the beam. Thus, a set of crystal grains having a width of 10 to 30 μm in the scanning direction of one crystal grain and a width of about 1 to 5 μm in the direction perpendicular to the scanning direction is formed on the entire surface of the laser irradiation region. can do. In this way, crystal grains comparable to those of a continuous wave laser can be obtained. By forming single crystal crystal grains extending along the beam scanning direction, it is possible to form a semiconductor film having almost no crystal grain boundaries in at least the TFT carrier movement direction.

  Further, when a laser oscillator using a polycrystalline medium is used, it is possible to emit a laser having a very high output. In such a case, the beam size can be increased. The length of the minor axis of the beam should be 1 mm or less, and the width of the major axis of the beam may be adjusted to such an extent that the semiconductor film can be annealed satisfactorily.

In the present invention, a laser beam converted into a harmonic by a nonlinear element can be used as the laser beam. Nonlinear elements include BBO (β-BaB ₂ O ₄ , barium borate), LBO (Li ₂ B ₄ O ₇ , lithium borate), KTP (KTiOPO ₄ , potassium titanyl phosphate), LiNbO ₃ (lithium niobate). ), KDP (KH ₂ PO ₄ , potassium dihydrogen phosphate), LiIO ₃ (lithium iodate), ADP (NH ₄ H ₂ PO ₄ , ammonium dihydrogen phosphate), BIBO (BiB ₃ O ₆ , bismuth triborate) ), CLBO (CsLiB ₆ O ₁₀ , cesium lithium borate), KB5 (KB ₅ O ₈ .4H ₂ O, potassium diborate).

  In the configuration of the invention, the incident angle of the laser beam emitted from the laser oscillator with respect to the irradiation surface can be set as appropriate.

  A thin film transistor (TFT) is formed from a crystalline semiconductor film formed by using the present invention, and a semiconductor device manufactured using the TFT is typically a CPU (Central Processing Unit), a memory. IC, RFID element, pixel, driver circuit, and the like. Further, by incorporating these semiconductor devices, various electronic devices such as a television, a computer, and a portable information processing terminal can be formed.

  A laser beam having a uniform intensity distribution can be irradiated without causing laser interference fringes on the irradiation surface. Therefore, the laser treatment can be uniformly performed on the semiconductor film.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings. However, the present invention can be implemented in many different modes, and without departing from the spirit and scope of the present invention. It will be readily appreciated by those skilled in the art that the details can be varied in many ways. Therefore, the present invention is not construed as being limited to the description of this embodiment mode.

(Embodiment 1)
The embodiment of the present invention will be described with reference to FIGS.

  FIG. 1 shows an example of a laser irradiation apparatus. The laser irradiation apparatus includes a laser oscillator 101, a diffractive optical element 102 (also referred to as a diffractive optics element or a diffractive optics), a slit 103, a projection lens 104, and a condenser lens 105. In the present embodiment, the projection lens 104 uses a convex cylindrical lens, but a convex spherical lens can also be used. Moreover, although the convex cylindrical lens is used as the condensing lens 105, a convex spherical lens can also be used. The mirror 106 may be provided according to the installation status of the optical system of the laser irradiation apparatus.

As the laser oscillator 101, a CW laser or a pulse laser having an oscillation frequency of 10 MHz or more can be used. Laser types include single crystal YAG, YVO ₄ , forsterite, YAlO ₃ , GdVO ₄ , polycrystalline YAG, Y ₂ O ₃ , YVO ₄ , YAlO ₃ , GdVO ₄ , or Nd as a dopant in an optical fiber. , Yb, Cr, Ti, Ho, Er, Tm, and Ta, a laser using a medium added with one or more, an Ar ion laser, a Ti: sapphire laser, or the like can be used. These can be oscillated with continuous oscillation. It is also possible to oscillate pulses at an oscillation frequency of 10 MHz or more by performing Q switch operation and mode synchronization.

  The laser beam emitted from the laser oscillator 101 has an intensity distribution having the shape shown in FIG. By passing the laser beam through the diffractive optical element 102, the shape of the cross section of the laser beam is shaped into a linear shape, a square shape, or an elliptical shape, and the intensity distribution of the laser beam is made uniform. The intensity distribution of the laser beam that has passed through the diffractive optical element 102 is shown in FIG. The diffractive optical element 102 is an element that obtains a spectrum using light diffraction, and an element having a condensing lens function by forming a large number of grooves on the surface thereof is used.

  Next, this beam is passed through the slit 103. The slit 103 is installed so that the cross section of the beam shaped into a linear, quadrangular, or elliptical shape acts by the diffractive optical element 102 in the long axis direction. The slit 103 has a structure or a shape that can block a weak region at both ends of the beam and can adjust the length of the beam in the long axis direction at the same time. There is no particular restriction on the above. For example, as shown in FIG. 3, an opening 301 is provided at the center of the slit 103, and both ends in the longitudinal direction of the opening 301 can be adjusted by opening and closing the shielding plate 302. The opening / closing method may be a motor driving method or a method of adjusting by turning a screw. When the laser beam passes through such a slit 103, the end portion in the long axis direction of the beam is blocked, and the laser beam which is the intensity distribution of the dotted line in FIG. 2C becomes the intensity distribution of the solid line in FIG. A laser beam with

  After passing through the slit 103, the laser beam passes through the projection lens 104. The projection lens 104 is arranged so that the image of the slit 103 is formed on the semiconductor film 107 that is the irradiation surface after passing through the projection lens 104. Details of the arrangement of the optical system of this embodiment will be described with reference to FIG. FIG. 4A shows an optical system used in this embodiment. FIG. 4B is a view of this from the top, and FIG. 4C is a view from the side.

As shown in FIG. 4B, the width of the opening of the slit 103 is a, the length of the major axis of the laser beam in the semiconductor film 107 is b, the focal length of the projection lens 104 is f, and the back surface of the slit 103 (beam There distance _{d 1} from the surface) on the side of the exit to the first principal point _{H 1} of the projection lens 104, and a distance from the second principal point of _{H 2} projection lens 104 to the semiconductor film 107 and _{d 2,} a, b, f, d ₁ , and d ₂ are set so as to satisfy the relationship of the following formulas (1) and (2). By arranging the optical system in this way, an image having a length a at the opening of the slit 103 is projected onto the semiconductor film 107 as an image having a length b in the major axis direction by the projection lens 104.
1 / f = 1 / d ₁ + 1 / d ₂ (1)
d ₁ : d ₂ = a: b (2)

  Further, as shown in FIGS. 4B and 4C, it is preferable to focus the laser beam in the minor axis direction of the laser beam. Therefore, in this embodiment, a convex cylindrical lens is used as the condenser lens 105. Since the convex cylindrical lens is provided with a curvature only in one direction, the beam can be expanded and contracted only in the direction of the curvature. In addition, the convex cylindrical lens may have a convex surface on either the incident side or the emission side, or may have convex surfaces on both sides, but considering the low aberration and accuracy surface, It is preferable to use one having a convex surface on the incident side. The material of the convex cylindrical lens is not limited. It should be noted that the position of the condenser lens 105 suffices as long as it is behind the slit 103, and can be arranged in front of the projection lens 104.

In this embodiment mode, the direction of the laser beam is changed by the mirror 106 so that the optical path of the laser beam is directed toward the semiconductor film 107, and then the laser beam is passed through the condenser lens 105. In the case of a laser with an output of 20 W, a linear, square, or elliptical beam spot having a major axis of the beam cross section of 0.5 to 1 mm and a minor axis of 20 μm or less (preferably 10 μm or less) is a semiconductor film 107. To be formed. In the case of using a laser whose medium is polycrystalline Y ₂ O ₃ , YAG, YVO ₄ , YAlO ₃ , or GdVO ₄ , a laser having a much higher intensity than that when a single crystal is used as a medium is emitted. Is possible. Therefore, the length in the major axis direction of the cross section of the laser beam irradiated to the semiconductor film 107 is not limited to the above length. Further, the direction of the laser beam after the direction is changed by the mirror 106 may be the incident direction to the semiconductor film 107 being vertical or oblique.

  Conventionally, diffracted light generated by passing through the slit reaches the semiconductor film and forms interference fringes, but by arranging an optical system as in this embodiment, no interference fringes are formed. The semiconductor film 107 can be irradiated with a laser beam having a uniform intensity distribution.

  The substrate over which the semiconductor film 107 is formed is made of an insulating material, and is fixed to the suction stage 108 so that it does not drop during laser irradiation. The adsorption stage 108 scans the surface parallel to the surface of the semiconductor film 107 in the X-axis and Y-axis directions using the X stage 109 and the Y stage 110 to crystallize the entire surface of the semiconductor film 107.

  In this embodiment mode, the substrate on which the semiconductor film 107 is formed is moved using the X stage 109 and the Y stage 110, but the laser beam scan is performed by fixing the substrate that is an object to be processed to a laser beam. An irradiation system moving type that moves the irradiation position of the beam, a workpiece moving type that moves the substrate while fixing the irradiation position of the laser beam, or a method that combines the above two methods can be used.

  By using these optical systems, the intensity distribution of the laser beam irradiated onto the irradiation surface is uniform, and the portion where the intensity at the beam end is insufficient can be removed. Further, the diffracted light generated by passing through the slit 103 does not reach the semiconductor film 107 and form interference fringes. With such a structure, the entire surface of the semiconductor film 107 can be favorably subjected to laser irradiation treatment.

  By manufacturing a semiconductor device using such a semiconductor film, the performance of the semiconductor device can be significantly improved. For example, taking a TFT as an example, the number of crystal grain boundaries included in a channel formation region can be reduced, so that field effect mobility (mobility) equal to or higher than that of a TFT using a single crystal semiconductor is obtained. ON current value (the value of the drain current that flows when the TFT is in an on state), OFF current value (the value of the drain current that flows when the TFT is in an off state), threshold voltage , Variation in S value and field effect mobility can be reduced. Because of such effects, the electrical characteristics of the TFT are improved, and the operating characteristics and reliability of the semiconductor device using the TFT are improved. In particular, since there are almost no grain boundaries in the laser moving direction, it is preferable to form a channel formation region of the TFT along this direction because it leads to improvement of TFT characteristics.

(Embodiment 2)
In this embodiment mode, another optical system that can be used in the laser irradiation apparatus of the present invention will be described.

  FIG. 5A is a diagram showing the optical system used in the present embodiment. FIG. 5 (b) shows a view from above and FIG. 5 (c) shows a view from the side.

  In Embodiment 1, a convex cylindrical lens is used for the projection lens 104 and a convex cylindrical lens is used for the condenser lens 105 as shown in FIG. In the present embodiment, a convex spherical lens is used as a projection lens, a convex cylindrical lens is used as a condenser lens, and a concave cylindrical lens is used as a correction lens. The parts other than the projection lens, the condensing lens, and the correction lens can be the same as those used in the first embodiment.

  As shown in FIG. 5A, the laser beam emitted from the laser oscillator 501 passes through the diffractive optical element 502 to make the beam shape and intensity uniform. Further, after the end of the beam in the long axis direction is blocked by the slit 503, the beam passes through the correction lens 507 and the projection lens 504. Then, the projection lens 504 is disposed so that the image of the slit 503 is formed on the semiconductor film 506.

In FIG. 5B, the width of the opening of the slit 503 is a, the length of the major axis of the laser beam in the semiconductor film 506 is b, the focal length of the projection lens 504 is f, and the projection lens is projected from the second surface of the slit 503. Assuming that the distance from the first principal point H _{1 of} 504 is d ₁ and the distance from the second principal point H ₂ of the projection lens 504 to the semiconductor film 506 is d ₂ , a, b, f, d ₁ , d ₂ are , Satisfy the relationship of the mathematical formulas (1) and (2) described above. By arranging the optical system in this way, an image having a length a at the opening of the slit 503 is projected onto the semiconductor film 506 by the projection lens 504.

  Further, as described in Embodiment Mode 1, it is preferable to focus the laser beam in the short axis direction of the laser beam. In the present embodiment, since the projection lens 504 is a convex spherical lens, the projection lens 504 focuses the laser beam in the major axis direction and the minor axis direction. Here, by using a convex spherical lens as the projection lens 504, spherical aberration can be suppressed small. In order to eliminate the influence of the projection lens 504 in the minor axis direction of the laser beam, a concave cylindrical lens is arranged as a correction lens 507 so as to act in the minor axis direction of the laser beam immediately before the projection lens 504.

  Although the mirror is not shown in this embodiment mode, it may be arranged between the projection lens 504 and the condenser lens 505 as in the first embodiment. At that time, the direction of the laser beam after the direction is changed by the mirror may be perpendicular or oblique to the semiconductor film 506. It should be noted that the position of the condenser lens 505 is only required to be behind the slit 503 and can be arranged in front of the correction lens 507 and the projection lens 504.

  By arranging the optical system in this way, the intensity distribution of the laser beam to be irradiated is uniform, and the portion where the intensity at the beam end is insufficient can be removed. Further, diffracted light generated by passing through the slit 503 does not reach the semiconductor film 506 and form interference fringes. With such a structure, the entire surface of the semiconductor film 506 can be irradiated with a beam having a uniform intensity distribution.

  In this embodiment, an example of a laser irradiation apparatus will be described. An example in which a crystal composed of a polycrystalline aggregate is used as a laser medium will be described.

  FIG. 6 shows an example of a laser irradiation apparatus. The laser irradiation apparatus includes a laser oscillator 601, a diffractive optical element 602, a slit 603, a projection lens 604, and a condenser lens 605. The laser oscillator 601 used in this embodiment uses a YAG crystal having a polycrystalline aggregate ceramic structure (hereinafter referred to as ceramic YAG) as a laser crystal, and emits a pulse laser beam having an oscillation frequency of 10 MHz or more. Further, although the mirror 606 is used in this embodiment, it may be provided according to the installation status of the optical system of the laser irradiation apparatus.

  As shown in FIG. 6, the laser beam emitted from the laser oscillator 601 enters the diffractive optical element 602. The diffractive optical element 602 shapes the cross section of the laser beam into a linear shape, a square shape, or an elliptical shape, and makes the intensity distribution of the laser beam uniform. The diffractive optical element 602 is an element that obtains a spectrum using light diffraction, and an element having a condensing lens function by forming a large number of grooves on the surface thereof is used. The light that has passed through the diffractive optical element 602 forms an image at the slit 603.

  The slit 603 has a structure or shape that can block a region where the intensity at both ends of the laser beam is weak and can adjust the length of the laser beam in the major axis direction at the same time, and the slit material, adjusting method, etc. There are no particular restrictions. When the end of the laser beam is cut off using such a slit 603, the laser beam becomes more uniform in intensity.

After passing through the slit 603, the beam is passed through the projection lens 604. Here, the projection lens 604 is arranged so that the image of the slit 603 is formed on the semiconductor film 607 after passing through the projection lens 604. That is, the projection lens 604 is arranged so that the image of the slit 603 and the semiconductor film 607 are in a conjugate relationship. At this time, the width of the opening of the slit 603 is a, the length of the major axis of the laser beam in the semiconductor film 607 is b, the focal length of the projection lens 604 is f, and from the back of the slit 603 to the first principal point of the projection lens. Where d _{1 is} the distance from the second principal point of the projection lens and d ₂ is the distance from the irradiation surface, a, b, f, d ₁ , and d ₂ are the expressions (1) and (2) shown above. Meet the relationship.

  With such an arrangement, it is possible to prevent the diffracted light generated by passing through the slit 603 from reaching the semiconductor film 607 and forming interference fringes, and a laser beam having a uniform intensity distribution is applied to the semiconductor film 607. Can be irradiated.

  Further, the direction of the laser beam is changed by the mirror 606 so that the optical path of the laser beam is directed toward the semiconductor film 607. Further, the incident direction of the laser beam after the direction is changed by the mirror 606 may be perpendicular or oblique to the semiconductor film 607.

  Thereafter, the condensing lens 605 condenses the laser beam using a convex spherical lens and a concave cylindrical lens. By using a convex spherical lens, the spherical aberration can be kept small, so that the laser beam can be condensed smaller. The concave cylindrical lens is used to reduce the influence of the convex spherical lens on the long axis direction of the laser beam, and is arranged immediately before the convex spherical lens so as to act on the long axis direction of the laser beam. To do. There are no restrictions on the structure and material of the convex spherical lens. For example, a convex surface may be formed on either the incident side or the exit side, or a convex surface may be formed on both sides. However, in consideration of low aberration and accuracy, a convex surface is formed on the incident side. It is preferable to use what has been used. If necessary, two or more convex cylindrical lenses may be used so as to act independently in the major axis direction and the minor axis direction of the laser beam.

  The substrate over which the semiconductor film 607 is formed is made of an insulating material. Specifically, glass substrates such as aluminoborosilicate glass and barium borosilicate glass, quartz substrates, ceramic substrates, stainless steel substrates, PET (Polyethylene Terephthalate), PES (Polyethersulfone Resin), A plastic typified by PEN (Polyethylene Naphthalate), a substrate made of a synthetic resin typified by acrylic, or the like can be used. The substrate is fixed to the suction stage 608 so that it does not fall during the laser irradiation process. The adsorption stage 608 uses an X stage 609 and a Y stage 610 to set the surface parallel to the surface of the semiconductor film 607 to 10 mm / sec. In the X axis and Y axis directions. The entire surface of the semiconductor film 607 can be crystallized by scanning at an appropriate speed.

  In this embodiment, ceramic YAG is used for the laser crystal. Ceramic YAG has almost the same optical properties (thermal conductivity, breaking strength, absorption cross section) as single crystal. Moreover, since it is ceramic, it can be formed into a free shape in a short time and at low cost, and the crystal can be made very large. Furthermore, it is possible to add a dopant concentration such as Nd and Yb higher than that of the single crystal. By using such a laser crystal as a medium, it is possible to emit a laser having a very high output. Therefore, by shaping this beam using an optical system, it is possible to obtain a linear beam having a minor axis length of 1 mm or less and a major axis length of several hundreds of millimeters to several meters. In general, the panel size of a display manufactured using a process using a linear beam is limited by the length of the linear beam. For this reason, it becomes possible to produce a larger display by obtaining a longer linear beam using the present invention.

Further, when a plurality of dopants such as Nd, Yb, Cr, Ti, Ho, Er, Tm, and Ta are added to ceramic YAG, oscillation occurs at a number of wavelengths. The center wavelength of the fundamental wave of this laser is 1030 to 1064 nm, and the full width at half maximum of the oscillation wavelength is about 30 nm. This fundamental wave is converted by a nonlinear optical crystal in the laser oscillator 601 into a second harmonic having a center wavelength of 515 to 532 nm and a full width at half maximum of the oscillation wavelength of about 15 nm. Further, not only ceramic YAG but also laser irradiation using ceramic Y ₂ O ₃ or ceramic YVO ₄ as a medium can be similarly performed.

In a single-wavelength laser, interference fringes are generated on the irradiated surface when the laser passes through the slit. However, when the laser shown in this embodiment is used, it can be seen from the following equation (3) that the intervals between the interference fringes for the respective wavelengths are different. In Expression (3), x is the distance between the interference fringes, d is the width of the slit, λ is the wavelength, and L is the distance between the slit and the irradiation surface. For this reason, when a laser beam having a wide oscillation wavelength region is used, the difference in intensity of light generated by interference can be canceled out, and the influence of interference can be reduced as compared with the case where a single wavelength laser is used.
x = λL / d (3)

  In this embodiment, a pulse beam in which the lower limit of the oscillation frequency is set so that the period (oscillation frequency) of pulse oscillation is shorter than the time from when the semiconductor film 607 melts until it completely solidifies is used. For example, the specific oscillation frequency is 10 MHz or more, and a frequency that is significantly higher than a frequency of several tens to several hundreds Hz that is normally used is used.

  The reason why it is preferable to use a pulsed laser having a high oscillation frequency is as follows. It is said that the time from when the semiconductor film is irradiated with the laser beam until the semiconductor film is completely solidified is several tens to several hundreds of nsec. Therefore, in a pulse laser having a low oscillation frequency, the semiconductor film is irradiated with the next pulse after the semiconductor film is melted and solidified by the laser. Accordingly, crystal grains are formed by each pulse, a grain boundary is formed at the boundary between adjacent crystal grains, and unevenness is generated on the surface of the semiconductor film.

  However, when a pulse laser having a high oscillation frequency is used, the semiconductor film is irradiated with the next pulse after the semiconductor film is melted by the laser and solidified. Therefore, unlike the case of using a pulsed laser having a low oscillation frequency, irradiation with moving the laser relative to the semiconductor film continuously forms a region in a molten state one after another, while the passage of time. There is a region that cools and solidifies. When the solid-liquid interface is continuously moved in the semiconductor film, crystals continuously grow in the laser scanning direction, and large crystal grains are formed. Further, as a feature of the pulse oscillation laser, when the energy is the same, the peak output per pulse can be increased by increasing the oscillation frequency. Therefore, the conversion efficiency of the laser beam into the second harmonic can be significantly increased. This makes it possible to easily obtain high-output harmonics, so that the productivity of this step can be greatly improved.

  By using the above method, it is possible not only to form crystal grains that are continuously grown in the scanning direction, but also to suppress the formation of microcrystalline regions and irregularities at the boundary between adjacent laser irradiation regions. Therefore, the entire semiconductor film 607 can be uniformly annealed.

  In this embodiment, an example of an optical system using a phase conjugate mirror will be described in order to obtain a laser beam more suitable for annealing a semiconductor film.

  When laser irradiation is performed on a semiconductor film, generally a laser beam with high intensity is irradiated. Therefore, when using a laser for such an application, it is necessary to increase the peak output and focus the laser beam to a high intensity. However, in the case of a high-power laser, the laser medium becomes inhomogeneous due to heat, and the laser beam is distorted at the emission stage. Therefore, it is difficult to collect light with high intensity. Even if the phases are aligned at the exit stage, diffraction occurs by passing through the slit, and the image projected on the irradiation surface is distorted. Therefore, by using a phase conjugate mirror, it is possible to obtain a laser beam having a high intensity and a uniform phase, so that it becomes easy to perform beam deformation and beam intensity adjustment using an optical system. When the laser beam thus treated is used, the semiconductor film can be annealed more satisfactorily. The phase conjugate mirror includes a method using a light-induced refractive index effect, a method using stimulated Brillouin scattering, a method using stimulated Raman scattering, and a method using the Kerr effect. A method may be used.

  As shown in FIG. 7A1, when a laser beam 701 having a plane wavefront passes through an object 702 having distortion, the wavefront is deformed. Reference numeral 703 denotes a wave whose wavefront is disturbed. When the wave 703 whose wavefront is deformed as shown in FIG. 7 (a2) is reflected by the ordinary mirror 704 and the reflected wave 705 passes through the object again, as shown in FIG. 7 (a3), the wave observed by the observer O is observed. The deformation amount of the wavefront of 706 is doubled.

  FIG. 8 shows a case where a phase conjugate mirror 710 is used instead of the mirror 704. In the case of the phase conjugate mirror 710, since the phase of the reflected wave 711 is inverted, the wavefront distortions cancel each other when passing through the object 702 having distortion again, and the wave 712 observed by the observer O is the wavefront distortion. (FIGS. 8A1 to 8A3). As a result, light can propagate while maintaining its shape.

  An example of a laser irradiation apparatus using a phase conjugate mirror is shown in FIG. The laser beam emitted from the laser oscillator 901 enters the diffractive optical element 902. The diffractive optical element 902 shapes the cross section of the laser beam into a linear, quadrangular, or elliptical shape and makes the intensity distribution of the laser beam uniform. The light that has passed through the diffractive optical element 902 forms an image on the slit 903 by the condenser lens 907.

  The slit 903 has a structure or shape that can block the regions at both ends where the intensity of the laser beam is weak and can adjust the length of the laser beam in the long axis direction at the same time. There is no particular restriction on the above. When the end of the laser beam is cut off using such a slit 903, the laser beam has a uniform intensity.

  After passing through the slit 903, the laser beam is split by the beam splitter 904, one is made incident on the semiconductor film 905, and the other is operated by the phase conjugate mirror 906. When a normal mirror is used instead of the phase conjugate mirror 906, the image is greatly distorted because the diffraction propagates twice as much as the distance between the slit and the mirror. However, when the phase conjugate mirror 906 is used, the wavefront disturbance generated from the slit 903 to the phase conjugate mirror 906 becomes an antiphase due to the conjugate reflection. Therefore, the phase is set so that the phase is matched on the irradiation surface, here the semiconductor film 905. Is compensated. Therefore, the image of the slit 903 is favorably formed on the irradiation surface. In the case of the laser irradiation apparatus having the configuration shown in FIG. 9, an image of the slit 903 is formed on the semiconductor film 905 at an equal magnification because a lens for expanding and contracting the beam spot is not disposed between the slit 903 and the semiconductor film 905. .

  Another example of the laser irradiation apparatus is shown in FIG. First, the wavefront is adjusted by operating the phase conjugate mirror 1003. Specifically, after being emitted from the laser oscillator 1000, the laser beam is split by the beam splitter 1004, one is incident on the diffractive optical element 1005, and the other is operated by the phase conjugate mirror 1003. When the phase conjugate mirror 1003 is used, the wavefront disturbance is reversed due to the conjugate reflection, so that the diffractive optical element 1005 performs phase compensation so that the phases match. After aligning the wavefronts of the laser beams, the intensity is made uniform by the diffractive optical element 1005, and at the same time, the cross-sectional shape of the laser beams is shaped. This is because it is easy to make the intensity uniform with the diffractive optical element 1005 when the wave fronts of the laser beams are aligned.

  By operating the diffractive optical element 1005, the laser beam has a linear, square, or elliptical cross section. Next, the slit 1006 is operated. The slit 1006 blocks a portion where the intensity of the laser beam is weak, so that the laser beam has an intensity suitable for annealing of the semiconductor film. Then, as shown in FIGS. 11A and 11B, the projection lens 1007 and the condenser lens 1008 are arranged so that an image when passing through the slit 1006 is projected by the semiconductor film 1009. Note that FIG. 11A is a view from the top, and FIG. 11B is a view from the side.

In FIG. 11A, the width of the opening of the slit 1006 is a, the length of the major axis of the laser beam in the semiconductor film 1009 is b, the focal length of the projection lens 1007 is f, and the projection lens 1007 from the back of the slit 1006 Assuming that the distance to the first principal point H ₁ is d ₁ and the distance from the second principal point H ₂ of the projection lens 1007 to the semiconductor film 1009 is d ₂ , a, b, f, d ₁ , d ₂ are (1) and (2) are satisfied.

  Further, the laser beam is condensed in the minor axis direction of the laser beam. In this embodiment, the projection lens 1007 uses a convex cylindrical lens, and the condenser lens 1008 uses a concave cylindrical lens and a convex spherical lens. In order to reduce the influence of the convex spherical lens in the long axis direction of the laser beam, a concave cylindrical lens is disposed immediately before the convex spherical lens so as to act in the long axis direction of the laser beam.

  The substrate over which the semiconductor film 1009 is formed is made of the insulating material shown in Example 1. The substrate is fixed to the suction stage so that it does not fall during the laser irradiation process. The adsorption stage uses an X stage 1010 and a Y stage 1011. The surface parallel to the surface of the semiconductor film is 10 mm / sec. In the X axis and Y axis directions. The semiconductor film can be moved at a speed higher than that, and the entire surface of the semiconductor film can be crystallized by scanning the stage at an appropriate speed.

  Further, when the phase conjugate mirror is used in the laser oscillator 1000, the distortion of the amplifier in the laser oscillator 1000 can be completely corrected. Therefore, it is possible to emit a laser beam with high intensity and the same phase. Therefore, it becomes easier to make the intensity of the beam uniform and shape the beam using the optical system.

  By arranging the optical system in this way, the intensity distribution of the laser beam to be irradiated is uniform, and the portion where the intensity at the beam end is insufficient can be removed. Furthermore, the diffracted light generated by passing through the slit does not reach the semiconductor film and form interference fringes. With such a configuration, the entire surface of the semiconductor film can be irradiated with a beam having a uniform intensity distribution.

  In this embodiment, a process of manufacturing a thin film transistor (TFT) using the laser annealing apparatus of the present invention is shown. Note that although a manufacturing method of a top gate type (forward stagger type) TFT is described in this embodiment, the present invention is similarly applied to a bottom gate type (reverse stagger type) TFT or the like as well as the top gate type TFT. be able to.

  As shown in FIG. 12A, a base film 1201 is formed over a substrate 1200 having an insulating surface. In this embodiment, a glass substrate is used as the substrate 1200. As the substrate used here, a glass substrate such as barium borosilicate glass or alumino borosilicate glass, a quartz substrate, a ceramic substrate, a stainless steel substrate, or the like can be used. In addition, substrates made of plastics typified by PET, PES, PEN, and synthetic resins typified by acrylic generally tend to have a lower heat-resistant temperature than other substrates. As long as it can withstand this process, it can be used.

  The base film 1201 is provided to prevent an alkali metal such as sodium or an alkaline earth metal contained in the substrate 1200 from diffusing into the semiconductor and adversely affecting the characteristics of the semiconductor element. Therefore, an insulating film such as silicon oxide, silicon nitride, or silicon nitride oxide that can suppress diffusion of alkali metal or alkaline earth metal into the semiconductor is used. Further, the base film 1201 may be either a single layer or a stacked structure. In this embodiment, a silicon nitride oxide film is formed to a thickness of 10 to 400 nm by a plasma CVD method (Chemical Vapor Deposition).

  Note that in the case where a substrate that includes alkali metal or alkaline earth metal, such as a glass substrate or a plastic substrate, is used as the substrate 1200, a base film may be provided to prevent diffusion of impurities. Although effective, a base film 1201 is not necessarily provided when a substrate such as a quartz substrate that does not cause much problem of impurity diffusion is used.

  Next, an amorphous semiconductor film 1202 is formed over the base film 1201. The amorphous semiconductor film 1202 is formed with a thickness of 25 to 100 nm (preferably 30 to 60 nm) by a known method (a sputtering method, an LPCVD method, a plasma CVD method, or the like). As the amorphous semiconductor film used here, silicon, silicon germanium, or the like can be used; here, silicon is used. When silicon germanium is used, the concentration of germanium is preferably about 0.01 to 4.5 atomic%.

  Subsequently, as shown in FIG. 12B, crystallization is performed by irradiating the amorphous semiconductor film 1202 with a laser 1203 using the laser annealing apparatus of the present invention. In this embodiment, a ceramic YAG laser having an oscillation frequency of 10 MHz or more is used as the laser 1203. A plurality of dopants such as Nd and Yb are added to the laser crystal of ceramic YAG to obtain oscillation at a large number of wavelengths. The center wavelength of the fundamental wave of this laser is 1030 to 1064 nm, and the full width at half maximum of the oscillation wavelength is about 30 nm. This fundamental wave is converted into a second harmonic having a center wavelength of 515 to 532 nm and a full width at half maximum of the oscillation wavelength of about 15 nm by a nonlinear optical crystal in the laser oscillator. In this embodiment, the laser 1203 is converted to the second harmonic by the nonlinear optical element, but may be a harmonic other than the second harmonic.

  The laser is not limited to the laser described here, and a CW laser shown in the embodiment mode and other examples, or a pulsed laser whose oscillation frequency exceeds 10 MHz can be used.

  The laser beam emitted from the laser oscillator is shaped into a linear, square, or elliptical shape by a diffractive optical element, and the intensity distribution of the laser beam is made uniform. Thereafter, the end of the beam having low intensity is blocked by the slit, and the length of the beam in the long axis direction is adjusted. By using a diffractive optical element and a slit, a laser beam with a more uniform intensity can be obtained. Further, the slit image is directly formed on the amorphous semiconductor film 1202 by passing a convex cylindrical lens or a convex spherical lens as a projection lens. Note that as shown in the embodiment mode and other examples, the amorphous semiconductor film 1202 is irradiated after being condensed using a cylindrical lens or a convex spherical lens.

  By using the above method, the diffracted light generated by passing through the slit does not reach the amorphous semiconductor film 1202 to form interference fringes, and a laser beam with a uniform intensity distribution is generated by the amorphous semiconductor. The film 1202 can be irradiated. By scanning the amorphous semiconductor film 1202 with this laser beam, not only crystal grains continuously grown in the scanning direction are formed, but also microcrystalline regions and irregularities are formed at the boundary between adjacent laser irradiation regions. The formation of can be suppressed. By irradiating the semiconductor film with the laser in this manner, the entire surface of the semiconductor film is uniformly annealed, and the characteristics of an electronic device manufactured using the semiconductor film can be made favorable and uniform.

  After that, as illustrated in FIG. 12C, the crystalline semiconductor film 1205 formed by laser beam irradiation is etched into a predetermined shape, so that an island-shaped semiconductor film 1206 is formed. Further, a gate insulating film 1207 is formed so as to cover the island-shaped semiconductor film 1206.

The gate insulating film 1207 may be an insulating film containing at least oxygen or nitrogen, and may be a single layer or a multilayer. As a film formation method at that time, a plasma CVD method or a sputtering method can be used. In this embodiment, silicon nitride oxide (SiN _x O _y (x> y, x, y = 1, 2, 3,...)) And silicon oxide silicon (SiO _x N _y (x > Y, where x, y = 1, 2, 3,...)) Were continuously formed to form a total film thickness of 115 nm. Note that in the case where a TFT having a channel length of 1 μm or less (also referred to as a submicron TFT) is formed, the gate insulating film is preferably formed with a thickness of 10 to 50 nm.

  Next, a conductive film is formed over the gate insulating film 1207 and etched into a predetermined shape, whereby the gate electrode 1208 is formed. The outline is as follows. First, the material of the conductive film formed on the gate insulating film 1207 may be a conductive film. In this embodiment, a laminated film of W (tungsten) and TaN (tantalum nitride) is used. A conductive film in which Mo, Al, and Mo are stacked in this order using (aluminum) and Mo (molybdenum), or a conductive film that is stacked in the order of Ti, Al, and Ti using Ti (titanium) and Al may be used. In addition, an element selected from gold (Au), silver (Ag), copper (Cu), platinum (Pt), aluminum (Al), molybdenum (Mo), tungsten (W), titanium (Ti), or these A synthetic material or a compound material containing an element as a main component can be used. Furthermore, a laminate of these materials can also be used.

  Then, a resist mask for patterning this conductive film is formed. First, a photoresist is applied on the conductive film by a spin coating method or the like, and exposure is performed. Next, heat treatment (pre-bake) is performed on the photoresist. The pre-baking temperature is 50 to 120 ° C., which is lower than the post-baking performed later. In this example, the heating temperature was 90 ° C. and the heating time was 90 seconds.

  Next, the exposed resist is developed by dropping a developer onto the photoresist or spraying the developer from a spray nozzle.

  Thereafter, the developed photoresist is subjected to a so-called post-bake in which heat treatment is performed at 125 ° C. for 180 seconds to remove moisture remaining in the resist mask, and at the same time, stability against heat is enhanced. A resist mask is formed by the above steps. The gate electrode 1208 is formed by etching the conductive film into a predetermined shape based on this resist mask.

  Note that as another method, the gate electrode 1208 may be directly formed over the gate insulating film 1207 by a droplet discharge method typified by a printing method or an inkjet method that can discharge a material to a predetermined place. Good.

  As a material to be discharged, a material obtained by dissolving or dispersing a conductive material in a solvent is used. Materials used for the conductive film are gold (Au), silver (Ag), copper (Cu), platinum (Pt), aluminum (Al), chromium (Cr), palladium (Pd), indium (In), molybdenum (Mo) ), Nickel (Ni), lead (Pb), iridium (Ir), rhodium (Rh), tungsten (W), cadmium (Cd), zinc (Zn), iron (Fe), titanium (Ti), zirconium (Zr) ), Barium (Ba) or other metals, or an alloy of these metals. As the solvent, esters such as butyl acetate and ethyl acetate, alcohols such as isopropyl alcohol and ethyl alcohol, organic solvents such as methyl ethyl ketone and acetone can be used.

  Further, the viscosity of the composition is 0.3 Pa · s or less. This is for preventing drying and smoothly discharging the composition from the discharge port. Note that the viscosity and surface tension of the composition may be appropriately adjusted according to the solvent to be used and the application.

  Then, by using the resist used for forming the gate electrode 1208 or the gate electrode 1208 as a mask, by selectively adding an impurity imparting n-type or p-type conductivity to the island-shaped semiconductor film 1206, A source region 1209, a drain region 1210, an LDD region 1211, and the like are formed. Through the above steps, the N-channel TFTs 1212 and 1213 and the P-channel TFT 1214 can be formed over the same substrate (FIG. 12D).

  Subsequently, as shown in FIG. 12D, an insulating film 1215 is formed as a protective film thereof. This insulating film 1215 is formed by using a plasma CVD method or a sputtering method to form a silicon nitride film or a silicon nitride oxide film with a thickness of 100 to 200 nm as a single layer or a stacked structure. In the case of combining a silicon nitride oxide film and a nitrogen oxide silicon film, continuous film formation can be performed by switching gases. In this embodiment, a silicon oxynitride film having a thickness of 100 nm is formed by plasma CVD. By providing the insulating film 1215, it is possible to obtain a blocking action that prevents intrusion of various ionic impurities including oxygen and moisture in the air.

  Next, an insulating film 1216 is further formed. Here, an organic resin film such as polyimide, polyamide, BCB (benzocyclobutene), acrylic, siloxane (or the like) applied by an SOG (Spin On Glass) method or a spin coating method can be used. (Insulating film containing silicon such as silicon nitride and silicon oxide), a low-k (low dielectric constant) material, etc. The insulating film 1216 reduces unevenness caused by TFTs formed over the glass substrate, A film having excellent flatness is preferable because of the strong meaning of flattening, and siloxane has a skeletal structure composed of a bond of silicon (Si) and oxygen (O), and the substituent is an organic material containing at least hydrogen. It is a material that is either a group (for example, an alkyl group, aromatic hydrocarbon) or a fluoro group. It may contain both an organic group and a fluoro group.

  Further, the gate insulating film 1207, the insulating film 1215, and the insulating film 1216 are patterned using photolithography to form contact holes that reach the source region 1209 and the drain region 1210.

  Next, a conductive film is formed using a conductive material, and the wiring 1217 is formed by patterning the conductive film. After that, when an insulating film 1218 is formed as a protective film, a semiconductor device as shown in FIG. 12D is completed.

  A method for manufacturing a semiconductor device using the laser annealing method of the present invention is not limited to the above-described TFT manufacturing process. By using a semiconductor film crystallized by the laser beam irradiation method of the present invention as an active layer of a TFT, variations in mobility, threshold value, and on-current between elements can be suppressed.

  Further, a crystallization step using a catalytic element may be provided before crystallization with a laser beam. The catalyst elements are nickel (Ni), germanium (Ge), iron (Fe), palladium (Pd), tin (Sn), lead (Pb), cobalt (Co), platinum (Pt), copper (Cu). An element such as gold (Au) can be used.

  Note that after adding a catalytic element and performing heat treatment to promote crystallization, laser beam irradiation may be performed, or the heat treatment step may be omitted. Further, after the heat treatment, the laser treatment may be performed while maintaining the temperature.

  In this embodiment, an example in which the laser irradiation method of the present invention is used for crystallization of a semiconductor film is shown, but the semiconductor film may be used to activate an impurity element doped. The method for manufacturing a semiconductor device using the present invention can also be used for a method for manufacturing an integrated circuit or a semiconductor display device.

  In addition, when the present invention is used, the semiconductor film is uniformly annealed. Therefore, all TFTs manufactured using the semiconductor film formed by the method of the present invention have good characteristics, and the characteristics of individual TFTs are uniform.

  In addition, this embodiment can be freely combined with the embodiment mode and other embodiments.

  In this embodiment, an example in which crystallization is performed more satisfactorily by combining a crystallization method using a laser irradiation apparatus of the present invention with a crystallization method using a catalytic element will be described.

  First, as shown in FIG. 13A, steps up to forming a base film 1301 over a substrate 1300 and forming a semiconductor film 1302 over the base film 1301 are performed with reference to Embodiment 2. Next, as illustrated in FIG. 13B, a solution containing 10 to 100 ppm of Ni in terms of weight, for example, a solution of nickel acetate, is applied to the surface of the semiconductor film 1302 by a spin coating method, and the surface of the semiconductor film 1302 A region into which nickel is introduced is formed in the vicinity. Note that the dotted line in FIG. 13B indicates that a catalyst element has been introduced. The introduction of the catalyst is not limited to the above method, and may be introduced using a sputtering method, a vapor deposition method, a plasma treatment, or the like.

  And it heat-processes at 500-650 degreeC for 4 to 24 hours, for example, 500 degreeC and 14 hours. By this heat treatment, crystallization is performed in a vertical direction from the region where the catalytic element is introduced toward the region where the catalytic element is not introduced, that is, as indicated by an arrow, from the surface of the semiconductor film 1302 toward the substrate 1300. A promoted and crystallized semiconductor film 1303 is formed (FIG. 13C).

  The heat treatment may be performed by RTA (Rapid Thermal Anneal) using the radiation of the lamp as a heat source or RTA (gas RTA) using a heated gas at a set heating temperature of 740 ° C. for 180 seconds. The set heating temperature here is the temperature of the substrate measured with a pyrometer, and this temperature is set as the set temperature during heat treatment. In addition, there is a heat treatment for 4 hours at 550 ° C. using a furnace annealing furnace, which may be used for heat treatment. The lowering and shortening of the crystallization temperature is due to the action of a catalytic metal element.

  In this embodiment, nickel (Ni) is used as a catalyst element. In addition, germanium (Ge), iron (Fe), palladium (Pd), tin (Sn), lead (Pb), cobalt Elements such as (Co), platinum (Pt), copper (Cu), and gold (Au) may be used.

  Next, as illustrated in FIG. 13D, the semiconductor film 1303 is crystallized using a laser irradiation apparatus. The laser oscillator used in this example is a Ti: sapphire laser. A Ti: sapphire laser is a laser that enables multi-wavelength oscillation with one kind of dopant. The center wavelength of the fundamental wave of the laser beam 1304 is 660 to 1180 nm. This fundamental wave is converted into a second harmonic wave having a center wavelength of 330 to 540 nm by a nonlinear optical crystal in the laser oscillator, and irradiated with an oscillation frequency of 10 MHz or more. In the present embodiment, the second harmonic is used, but a harmonic other than the second harmonic may be used.

  As the laser, the CW laser shown in the embodiment mode or other examples, or a pulse laser having an oscillation frequency exceeding 10 MHz can be used.

  The laser beam 1304 emitted from the laser oscillator is made uniform by the diffractive optical element so that the intensity distribution of the beam is uniform. Further, a convex cylindrical lens is used as a projection lens in the major axis direction of the laser beam 1304, and an image of the slit is directly formed on the semiconductor film. In this manner, the semiconductor film is irradiated with the laser beam 1304 having a uniform cross-sectional intensity.

  By performing the laser irradiation method described above, not only crystal grains that are continuously grown in the scanning direction are formed, but also the formation of microcrystalline regions and irregularities at the boundary between adjacent laser irradiation regions is suppressed. can do.

By irradiating the semiconductor film 1303 with the laser beam 1304, a semiconductor film 1305 with higher crystallinity is formed. Note that it is considered that the semiconductor element 1305 crystallized using the catalytic element contains the catalytic element (Ni in this case) at a concentration of about 1 × 10 ¹⁹ atoms / cm ³ . Next, gettering of the catalytic element present in the semiconductor film 1305 is performed. Since gettering can remove a metal element mixed in the semiconductor film, off-state current can be reduced.

  First, as illustrated in FIG. 14A, an oxide film 1306 is formed on the surface of the semiconductor film 1305. By forming the oxide film 1306 having a thickness of about 1 nm to 10 nm, the surface of the semiconductor film 1305 can be prevented from being roughened by etching in a later etching step. Note that the oxide film 1306 can be formed by a known method. For example, it may be formed by oxidizing the surface of the semiconductor film 1305 with an aqueous solution in which sulfuric acid, hydrochloric acid, nitric acid, and the like are mixed with hydrogen peroxide water, ozone water, or plasma treatment in an atmosphere containing oxygen. Alternatively, it may be formed by heat treatment, ultraviolet irradiation or the like. In addition, an oxide film may be separately formed by a plasma CVD method, a sputtering method, a vapor deposition method, or the like.

Next, a gettering semiconductor film 1307 containing a rare gas element at a concentration of 1 × 10 ²⁰ atoms / cm ³ or higher is formed over the oxide film 1306 with a thickness of 25 to 250 nm by a sputtering method. The gettering semiconductor film 1307 preferably has a lower film density than the semiconductor film 1305 in order to increase the etching selectivity between the semiconductor film 1305 and the semiconductor film 1305. As the rare gas element, one or more selected from helium (He), neon (Ne), argon (Ar), krypton (Kr), and xenon (Xe) are used.

  Next, as shown in FIG. 14B, heat treatment is performed using a furnace annealing method or an RTA method to perform gettering. In the case of performing furnace annealing, heat treatment is performed at 450 to 600 ° C. for 0.5 to 12 hours in a nitrogen atmosphere. When using the RTA method, the lamp light source for heating is turned on for 1 to 60 seconds, preferably 30 to 60 seconds, and this is repeated 1 to 10 times, preferably 2 to 6 times. The emission intensity of the lamp light source is arbitrary, but the semiconductor film is instantaneously heated to 600 to 1000 ° C., preferably about 700 to 750 ° C.

  By the heat treatment, the catalyst element in the semiconductor film 1305 moves to the gettering semiconductor film 1307 as indicated by an arrow by diffusion and is gettered.

Next, the gettering semiconductor film 1307 is selectively etched and removed. Etching can be performed by dry etching without using plasma with ClF ₃ or wet etching with an alkaline solution such as an aqueous solution containing hydrazine or tetramethylammonium hydroxide ((CH ₃ ) ₄ NOH). At this time, the semiconductor film 1305 can be prevented from being etched by the oxide film 1306.

  Next, after the oxide film 1306 is removed with hydrofluoric acid, the semiconductor film 1305 is etched into a predetermined shape, so that an island-shaped semiconductor film 1308 is formed (FIG. 14C). Various semiconductor elements typified by TFTs can be formed using this island-shaped semiconductor film 1308. In the present invention, the gettering step is not limited to the method shown in this embodiment. Other methods may be used to reduce the catalytic element in the semiconductor film.

  Note that in this embodiment, the structure in which the crystallinity is further enhanced by laser beam irradiation after the catalyst element is added and then heat treatment is performed to promote crystallization has been described. The present invention is not limited to this, and the heat treatment step may be omitted. Specifically, after adding the catalyst element, the crystallinity may be improved by irradiating a laser beam instead of the heat treatment.

  In addition, this embodiment can be freely combined with the embodiment mode and other embodiments.

  A TFT manufactured using the present invention can also be used as a thin film integrated circuit device or a non-contact thin film integrated circuit device (also referred to as a wireless IC tag or an RFID (Radio Frequency Identification) tag). By using the manufacturing method shown in another embodiment, the thin film integrated circuit device or the non-contact type thin film integrated circuit device can be used as a tag or a memory.

  By using the present invention, it becomes possible to satisfactorily perform laser irradiation treatment on the entire surface of the semiconductor film, so that the degree of freedom of layout and size of the semiconductor element can be increased and the degree of integration can be improved. It becomes possible. In addition, the product quality of the manufactured thin film integrated circuit device and non-contact type thin film integrated circuit device is in a good state, and it becomes possible to suppress variations in quality. A specific example will be described with reference to the drawings.

  An example in which an insulated TFT is used as a semiconductor element used in an integrated circuit of a wireless IC tag is shown below. However, a semiconductor element used in an integrated circuit of a wireless IC tag is not limited to a TFT, and any element can be used. Can be used. For example, in addition to the TFT, a memory element, a diode, a photoelectric conversion element, a resistance element, a coil, a capacitor element, an inductor, and the like can be typically given.

  First, as illustrated in FIG. 15A, a separation layer 1501 is formed over a first substrate 1500 formed using a glass substrate by a sputtering method. The peeling layer 1501 can be formed by a sputtering method, a low pressure CVD method, a plasma CVD method, or the like. In this embodiment, amorphous silicon having a thickness of about 50 nm is formed by a low pressure CVD method and used as the peeling layer 1501. Note that the peeling layer 1501 is not limited to silicon, and may be formed using a material that can be selectively removed by etching (for example, W, Mo, or the like). The thickness of the release layer 1501 is desirably 50 to 60 nm.

  Next, a base insulating film 1502 is formed over the peeling layer 1501. The base insulating film 1502 is provided to prevent an alkali metal such as Na or an alkaline earth metal contained in the first substrate from diffusing into the semiconductor film and adversely affecting the characteristics of a semiconductor element such as a TFT. The base insulating film 1502 also has a role of protecting the semiconductor element in a process of peeling the semiconductor element later. The base insulating film 1502 may be a single layer or a stack of a plurality of insulating films. Therefore, an insulating film such as silicon oxide, silicon nitride, silicon oxide containing nitrogen (SiON), or silicon nitride containing oxygen (SiNO) that can suppress diffusion of alkali metal or alkaline earth metal into the semiconductor film is used. Form.

  Next, a semiconductor film 1503 is formed over the base insulating film 1502. The semiconductor film 1503 is preferably formed without being exposed to the air after the base insulating film 1502 is formed. The thickness of the semiconductor film 1503 is 20 to 200 nm (desirably 40 to 170 nm, preferably 50 to 150 nm).

  Then, as in the embodiment mode and other examples, the semiconductor film 1503 is irradiated with a laser beam 1499 to crystallize the semiconductor film 1503. By irradiation of the semiconductor film 1503 with the laser beam 1499, the crystalline semiconductor film 1504 is formed. Note that FIG. 15A is a cross-sectional view illustrating the middle of scanning with the laser beam 1499.

  By using the present invention, a laser beam having a uniform intensity can be obtained without causing laser interference fringes on the irradiated surface. By using this laser beam, it is possible to uniformly perform laser processing on the semiconductor film.

  Next, as illustrated in FIG. 15B, the semiconductor film 1504 having a crystal structure is etched into a predetermined shape to form island-shaped semiconductor films 1505 to 1507, and then a gate insulating film 1508 is formed. The gate insulating film 1508 can be formed using a single layer or a stacked layer of silicon nitride, silicon oxide, silicon oxide containing nitrogen, or silicon nitride containing oxygen using a plasma CVD method, a sputtering method, or the like. it can.

  Note that after forming the gate insulating film 1508, heat treatment is performed at 300 to 450 ° C. for 1 to 12 hours in an atmosphere containing 3 to 100% hydrogen to hydrogenate the island-shaped semiconductor films 1505 to 1507. May be performed. Further, plasma hydrogenation (using hydrogen excited by plasma) may be performed as another means of hydrogenation.

  Next, as shown in FIG. 15C, gate electrodes 1509 to 1511 are formed. Here, after forming Si and W so as to be stacked by sputtering, gate electrodes 1509 to 1511 are formed by performing etching using the resist 1512 as a mask. Needless to say, the conductive material, structure, and manufacturing method of the gate electrodes 1509 to 1511 are not limited to these, and can be selected as appropriate. For example, a stacked structure of Si and NiSi (nickel silicide) doped with an n-type impurity or a stacked structure of TaN (tantalum nitride) and W (tungsten) may be used. Alternatively, a single layer may be formed using various conductive materials. In the case where the gate electrode and the antenna are formed at the same time, materials may be selected in consideration of their functions.

Further, instead of a resist mask, a mask such as SiO _x may be used. In this case, a process of forming a mask (referred to as a hard mask) of SiO _x , SiON or the like by etching into a predetermined shape is added. However, since the film thickness of the mask during etching is less than that of the resist, Gate electrodes 1509 to 1511 can be formed. Alternatively, the gate electrodes 1509 to 1511 may be selectively formed by a droplet discharge method without using the resist 1512.

  Next, as illustrated in FIG. 15D, an island-shaped semiconductor film 1506 to be a P-channel TFT is covered with a resist 1513, and the gate electrodes 1509 and 1511 are used as masks to form island-shaped semiconductor films 1505 and 1507 with n. An impurity element imparting a mold (typically, P (phosphorus) or As (arsenic)) is doped at a low concentration. By this doping step, doping is performed through the gate insulating film 1508, and a pair of low-concentration impurity regions 1516 and 1517 are formed in the island-shaped semiconductor films 1505 and 1507. Note that this doping step may be performed without covering the island-shaped semiconductor film 1506 to be a P-channel TFT with the resist 1513.

  Next, as shown in FIG. 15E, after removing the resist 1513 by ashing or the like, a resist 1518 is newly formed so as to cover the island-shaped semiconductor films 1505 and 1507 to be N-channel TFTs, and the gate Using the electrode 1510 as a mask, the island-shaped semiconductor film 1506 is doped with an impurity element imparting P-type (typically, B (boron)) at a high concentration. By this doping step, doping is performed through the gate insulating film 1508, and a pair of P-type high concentration impurity regions 1520 are formed in the island-shaped semiconductor film 1506.

  Next, as illustrated in FIG. 16A, after the resist 1518 is removed by ashing or the like, an insulating film 1521 is formed so as to cover the gate insulating film 1508 and the gate electrodes 1509 to 1511.

After that, the insulating film 1521 and the gate insulating film 1508 are partially etched by an etch back method, and the side walls 1522 to 1524 in contact with the side walls of the gate electrodes 1509 to 1512 are self-aligned as shown in FIG. (Self-aligned). As an etching gas, a mixed gas of CHF ₃ and He was used. Note that the step of forming the sidewall is not limited to these.

  Next, as shown in FIG. 16C, a resist 1526 is newly formed so as to cover the island-shaped semiconductor film 1506 to be a P-channel TFT, and the gate electrodes 1509 and 1511 and the sidewalls 1522 and 1524 are masked. As described above, an impurity element imparting n-type (typically P or As) is doped at a high concentration. In this doping step, doping is performed through the gate insulating film 1508, and a pair of n-type high concentration impurity regions 1527 and 1528 are formed in the island-shaped semiconductor films 1505 and 1507.

Next, after removing the resist 1526 by ashing or the like, the impurity regions may be thermally activated. For example, after a 50 nm SiON film is formed, heat treatment may be performed in a nitrogen atmosphere at 550 ° C. for 4 hours. In addition, after forming a SiN _x film containing hydrogen to a thickness of 100 nm, defects in the polycrystalline semiconductor film can be improved by performing heat treatment at 410 ° C. for 1 hour in a nitrogen atmosphere. This terminates dangling bonds existing in the polycrystalline semiconductor film, for example, and is called a hydrogenation process.

  Through the series of steps described above, an N-channel TFT 1530, a P-channel TFT 1531, and an N-channel TFT 1532 are formed. In the manufacturing process, a TFT having a channel length of 0.2 μm to 2 μm can be formed by appropriately changing the conditions of the etch back method and adjusting the size of the sidewall.

  Further, a passivation film for protecting the N-channel TFTs 1530 and 1532 and the P-channel TFT 1531 may be formed thereafter.

  Next, as shown in FIG. 17A, a first interlayer insulating film 1533 is formed so as to cover the N-channel TFTs 1530 and 1532 and the P-channel TFT 1531.

  Further, a second interlayer insulating film 1534 is formed over the first interlayer insulating film 1533. Note that the first interlayer insulating film 1533 or the second interlayer insulating film 1534 and the first interlayer insulating film 1533 or the first interlayer insulating film 1533 or the second interlayer insulating film 1534 due to a stress generated from a difference in thermal expansion coefficient between a conductive material or the like that forms a wiring to be formed later. In order to prevent peeling or cracking of the second interlayer insulating film 1534, a filler may be mixed in the first interlayer insulating film 1533 or the second interlayer insulating film 1534.

  Next, as shown in FIG. 17A, contact holes are formed in the first interlayer insulating film 1533, the second interlayer insulating film 1534, and the gate insulating film 1508, and N-channel TFTs 1530 and 1532 and a P-channel TFT 1531 are formed. Wirings 1535 to 1539 connected to are formed. Wirings 1535 and 1536 are in the high-concentration impurity region 1527 of the N-channel TFT 1530, wirings 1536 and 1537 are in the high-concentration impurity region 1520 of the P-channel TFT 1531, and wirings 1538 and 1539 are in the high-concentration impurity region of the N-channel TFT 1532. 1528, respectively. Further, the wiring 1539 is connected to the gate electrode 1511 of the N-channel TFT 1532. The N-channel TFT 1532 can be used as a memory element of a random number ROM.

  Next, as illustrated in FIG. 17B, a third interlayer insulating film 1541 is formed over the second interlayer insulating film 1534 so as to cover the wirings 1535 to 1539. The third interlayer insulating film 1541 is formed to have an opening at a position where the wiring 1535 is partially exposed. Note that the third interlayer insulating film 1541 can be formed using a material similar to that of the first interlayer insulating film 1533.

  Next, an antenna 1542 is formed over the third interlayer insulating film 1541. The antenna 1542 is formed using a conductive material including one or more metals such as Ag, Au, Cu, Pd, Cr, Mo, Ti, Ta, W, Al, Fe, Co, Zn, Sn, and Ni, and a metal compound. Can do. The antenna 1542 is connected to the wiring 1535. Note that in FIG. 17B, the antenna 1542 is directly connected to the wiring 1535; however, the wireless IC tag of the present invention is not limited to this structure. For example, the antenna 1542 and the wiring 1535 may be electrically connected using a separately formed wiring.

  The antenna 1542 can be formed by a printing method, a photolithography method, an evaporation method, a droplet discharge method, or the like. In FIG. 17B, the antenna 1542 is formed using a single-layer conductive film; however, an antenna 1542 in which a plurality of conductive films are stacked can be formed. For example, the antenna 1542 may be formed by coating a wiring formed of Ni or the like with electroless plating.

  The droplet discharge method means a method of forming a predetermined pattern by discharging droplets containing a predetermined composition from the pores, and includes an ink jet method and the like in its category. The printing method includes a screen printing method and an offset printing method. By using a printing method or a droplet discharge method, the antenna 1542 can be formed without using an exposure mask. In addition, unlike the photolithography method, there is no waste of material that is removed by etching in the droplet discharge method and the printing method. Further, since it is not necessary to use an expensive mask for exposure, the cost for manufacturing a wireless IC tag can be suppressed.

  In the case of using a droplet discharge method or various printing methods, for example, conductive particles in which Cu is coated with Ag can be used. Note that in the case where the antenna 1542 is formed by a droplet discharge method, it is preferable that treatment for increasing the adhesion of the antenna 1542 be performed on the surface of the third interlayer insulating film 1541.

  As a method for improving the adhesion, specifically, for example, a method of attaching a metal or a metal compound capable of enhancing the adhesion of the conductive film or the insulating film to the surface of the third interlayer insulating film 1541 by catalytic action. There is. In addition, an organic insulating film with high adhesion to the formed conductive film or insulating film, a method of attaching a metal or a metal compound to the surface of the third interlayer insulating film 1541, a surface of the third interlayer insulating film 1541 And a method of surface modification by plasma treatment under atmospheric pressure or reduced pressure.

  When the metal or metal compound attached to the third interlayer insulating film 1541 has conductivity, the sheet resistance is controlled so that the normal operation of the antenna is not hindered. Specifically, the average thickness of the conductive metal or metal compound is controlled to be, for example, 1 to 10 nm, or these metals or metal compounds are partially or entirely insulated by oxidation. Or just make it. Alternatively, the deposited metal or metal compound may be selectively removed by etching except for the region where the adhesion is desired to be improved. Alternatively, the metal or the metal compound may be selectively attached only to a specific region by using a droplet discharge method, a printing method, a sol-gel method, or the like, instead of attaching the metal or the metal compound to the entire surface of the substrate in advance. Note that the metal or metal compound does not need to be a completely continuous film on the surface of the third interlayer insulating film 1541, and may be dispersed to some extent.

  Then, as shown in FIG. 18A, after the antenna 1542 is formed, a protective layer 1545 is formed over the third interlayer insulating film 1541 so as to cover the antenna 1542. The protective layer 1545 is formed using a material that can protect the antenna 1542 when the peeling layer 1501 is removed later by etching. For example, the protective layer 1545 can be formed by applying an epoxy resin, an acrylate resin, or a silicon resin soluble in water or alcohols to the entire surface.

  Next, as shown in FIG. 18B, a groove 1546 is formed in order to separate the wireless IC tags individually. The groove 1546 may be formed so long as the peeling layer 1501 is exposed. The groove 1546 can be formed by dicing, scribing, or the like. Note that in the case where it is not necessary to separate the wireless IC tag formed over the first substrate 1500, the groove 1546 is not necessarily formed.

Next, as illustrated in FIG. 18C, the peeling layer 1501 is removed by etching. Here, halogen fluoride is used as an etching gas, and this gas is introduced from the groove 1546. For example, ClF ₃ (chlorine trifluoride) is used, the temperature is 350 ° C., the flow rate is 300 sccm, the atmospheric pressure is 798 Pascal (798 Pa), and the treatment time is 3 hours. Further, a gas in which nitrogen is mixed with ClF ₃ gas may be used. By using halogen fluoride such as ClF ₃ , the separation layer 1501 is selectively etched, so that the first substrate 1500 can be separated from the N-channel TFTs 1530 and 1532 and the P-channel TFT 1531. The halogen fluoride may be either a gas or a liquid.

  Next, as illustrated in FIG. 19A, the peeled N-channel TFTs 1530 and 1532, the P-channel TFT 1531 and the antenna 1542 are attached to the second substrate 1551 with an adhesive 1550. As the adhesive 1550, a material capable of bonding the second substrate 1551 and the base insulating film 1502 is used. As the adhesive 1550, for example, various curable adhesives such as a reactive curable adhesive, a thermosetting adhesive, a photocurable adhesive such as an ultraviolet curable adhesive, and an anaerobic adhesive can be used.

  Note that the second substrate 1551 can be formed using an organic material such as flexible paper or plastic.

  Next, as illustrated in FIG. 19B, after removing the protective layer 1545, an adhesive 1552 is applied over the third interlayer insulating film 1541 so as to cover the antenna 1542, and a cover material 1553 is attached. The cover material 1553 can be formed using a flexible organic material such as paper or plastic similarly to the second substrate 1551. The thickness of the adhesive 1552 may be, for example, 10 to 200 μm.

  For the adhesive 1552, a material capable of bonding the cover material 1553 to the third interlayer insulating film 1541 and the antenna 1542 is used. As the adhesive 1552, for example, various curable adhesives such as a reaction curable adhesive, a thermosetting adhesive, a photocurable adhesive such as an ultraviolet curable adhesive, and an anaerobic adhesive can be used.

  The wireless IC tag is completed through the above-described steps. By the above manufacturing method, an extremely thin integrated circuit having a total film thickness of 0.3 to 3 μm, typically about 2 μm, can be formed between the second substrate 1551 and the cover material 1553.

Note that the thickness of the integrated circuit includes not only the thickness of the semiconductor element itself but also the thicknesses of various insulating films and interlayer insulating films formed between the adhesive 1550 and the adhesive 1552. Further, the area occupied by the integrated circuit in the wireless IC tag, 5 mm square (25 mm ²⁾ or less, and more preferably may be 0.3mm square (0.09 mm ²⁾ to 4 mm square (16 mm ²⁾ degree.

  Note that in this embodiment, a method for separating the substrate and the integrated circuit by providing a separation layer between the first substrate 1500 having high heat resistance and the integrated circuit and removing the separation layer by etching is described. The manufacturing method of the wireless IC tag of the present invention is not limited to this configuration. For example, a metal oxide film may be provided between a substrate having high heat resistance and the integrated circuit, and the integrated circuit may be peeled by weakening the metal oxide film by crystallization. Alternatively, a release layer using an amorphous semiconductor film containing hydrogen is provided between a substrate having high heat resistance and an integrated circuit, and the release layer is removed after being altered by irradiation with a laser beam. The integrated circuit may be peeled off. Alternatively, the integrated circuit may be separated from the substrate by mechanically removing the highly heat-resistant substrate on which the integrated circuit is formed or removing the substrate by etching with a solution or gas.

  Note that although an example in which the antenna is formed over the same substrate as the integrated circuit is described in this embodiment, the present invention is not limited to this structure. An antenna formed over another substrate and the integrated circuit may be bonded later to be electrically connected.

  Note that the frequency of radio waves generally used in RFID is 13.56 MHz and 2.45 GHz, and forming a wireless IC tag so that radio waves of these frequencies can be detected improves versatility. Is very important.

  The wireless IC tag of this embodiment has an advantage that radio waves are less likely to be shielded than an RFID formed using a semiconductor substrate, and the signal can be prevented from being attenuated by shielding the radio waves. Accordingly, since a semiconductor substrate is not necessary, the cost of the wireless IC tag can be significantly reduced.

  Note that in this embodiment, the example in which the integrated circuit is separated and attached to a flexible substrate is described; however, the present invention is not limited to this structure. For example, in the case where a substrate having a heat resistant temperature that can withstand heat treatment in a manufacturing process of an integrated circuit, such as a glass substrate, is used, the integrated circuit is not necessarily peeled off.

  In addition, this embodiment can be freely combined with the embodiment mode and other embodiments.

  A specific example of use of a wireless IC tag manufactured using a manufacturing method shown in another embodiment will be described below.

  By using the present invention, it becomes possible to satisfactorily perform laser irradiation treatment on the entire surface of the semiconductor film, so that the degree of freedom of layout and size of the semiconductor element can be increased and the degree of integration can be improved. It becomes possible. Compared with the prior art, a wireless IC tag using TFTs manufactured using the present invention has good quality and no quality variation.

  FIG. 20A shows a state where the wireless IC tag 2002 is attached to the passport 2001. Further, the wireless IC tag 2002 may be embedded in the passport 2001. Similarly, a wireless IC tag is pasted or embedded in a driver's license, credit card, banknote, coin, securities, gift certificate, ticket, traveler's check (T / C), health insurance card, resident's card, family register copy, etc. be able to. In this case, only information indicating authenticity is input to the wireless IC tag, and an access right is set so that information cannot be read or written illegally. This can be realized by using a TFT formed by using the present invention. By using it as a tag in this way, it becomes possible to distinguish it from a forged one.

  In addition, a wireless IC tag can be used as a memory. FIG. 20B illustrates an example in which the wireless IC tag 2011 is embedded in a label attached to a vegetable package. Further, a wireless IC tag may be attached or embedded in the package itself. The wireless IC tag 2011 includes a production stage process such as production place, producer, date of manufacture, processing method, product distribution process, price, quantity, usage, shape, weight, expiration date, various authentication information, etc. Can be recorded. Information from the wireless IC tag 2011 is received and read by the antenna unit 2013 of the wireless reader 2012 and displayed on the display unit 2014 of the reader 2012 so that wholesalers, retailers, and consumers can easily grasp the information. become. In addition, by setting access rights for each of producers, traders, and consumers, a system is incapable of reading, writing, rewriting, and erasing without access rights.

  The wireless IC tag can be used as follows. At the time of accounting, the fact that accounting has been completed is entered in the wireless IC tag, and a check means is provided at the exit to check whether accounting has been written on the wireless IC tag. If you try to leave the store without checking out, an alarm will sound. This method can prevent forgetting to pay and shoplifting.

  Furthermore, in consideration of customer privacy protection, the following method can be used. Read the product information from the wireless IC tag at the cash register, and (1) lock the data input to the wireless IC tag with a password, etc. (2) encrypt the data itself input to the wireless IC tag, (3) Either delete the data input to the wireless IC tag, or (4) destroy the data input to the wireless IC tag. These can be realized by using the memories mentioned in the other embodiments. Then, by providing a check means at the exit, it is checked whether any of the processes (1) to (4) has been performed, or whether the wireless IC tag data has not been processed. Check for accounting. In this way, it is possible to check whether or not there is a transaction in the store, and it is possible to prevent information on the wireless IC tag from being read outside the store against the will of the owner.

  Note that there are several methods for destroying the data input to the wireless IC tag (4). For example, (a) “0 (off)” or “1 (on)”, or both “0” and “1” is written in at least a part of the electronic data of the wireless IC tag, and the data is meaningless. And (b) a method in which a current is excessively applied to the wireless IC tag and a part of the wiring of the semiconductor element included in the wireless IC tag is physically destroyed.

  As a method of using other wireless IC tags, the quality control method and handling method of products are automatically adjusted by reading information on products with wireless IC tags with a reader of household appliances such as refrigerators and washing machines. It becomes possible to make it. Further, it is possible to display product information by attaching a monitor to a household appliance.

  For example, a product (for example, food) has a temperature state and a humidity state suitable for storage. Moreover, it is important from the viewpoint of energy saving to set the temperature in the refrigerator for each season. However, it is very troublesome for consumers to adjust this by themselves. However, neglecting adjustments can quickly damage the product or, depending on the season, consume more power than necessary.

  FIG. 21A shows a state where a product 2101 with a wireless IC tag 2100 is taken in and out of the refrigerator 2102. The flow of data read here is shown in FIG. FIG. 22 shows a flowchart of processing performed by the refrigerator as goods 2101 are put in and out.

First, as shown in FIG. 21A, a product 2101 with a wireless IC tag is put in and out of the refrigerator 2102 (step S1). At this time, the reader 2103 reads information on the product that has been taken in and out (step S2). Next, the product data is transmitted to the arithmetic device 2104 of the refrigerator 2102 (step S3), and the arithmetic device 2104 stores the product data in the storage device 2105 as necessary. This data includes the type of product, the temperature (T ₁ ) optimal for storage, the humidity state, the expiration date, and the like. At the same time, the temperature (T ₂ ) and humidity state of the refrigerator 2102 are measured (step S4) and transmitted to the arithmetic device 2104 (step S5). This data is stored in the storage device 2105 as necessary. In the following description, attention is paid to the temperature, but other elements can be similarly processed.

Next, the arithmetic device 2104 takes out the data of the temperature (T ₁ ) optimal for storing the taken-in / out merchandise and the temperature (T ₂ ) in the refrigerator from the storage device 2105, and calculates the absolute value of the difference between T ₁ and T ₂ ( T ₃ ) is calculated, and whether T ₃ and the constant value (a) are as shown in the following formula (4) is compared (step S6).
| T ₁ −T ₂ | = T ₃ <a (4)

If T ₃ is a constant value (a) above, that is, when the above formula is false, since it is unsuitable to refrigerate 2102, a warning to the consumer by means such as sound, light (Step S7), temperature change of the refrigerator 2102 is not performed. If T ₃ is within a predetermined value (a), that is, when the above equation is true, following the following process.

The computing device 2104 calculates a temperature (T ₄ ) optimal for storing the product after taking in and out (step S8). Further, the temperature (T ₄ ) is compared with the temperature (T ₂ ) in the refrigerator (step S9), and the strength of cooling is determined based on the result. In the case of T ₂ > T ₄ , a control signal is transmitted to the adjusting device 2106 so as to weaken the cooling (step S10), and in the case of T ₂ <T ₄ , the control signal is sent to the adjusting device 2106 so as to increase the cooling. Transmit (step S11). Adjustment device 2106 operates in accordance with the control signal (step S12), the temperature of the refrigerator 2102 is adjusted to _{T 4.}

  Note that in the refrigerator 2102, input / output of the reader 2103, the arithmetic device 2104, and the adjustment device 2106 is controlled by the control device 2107. Note that a CPU may be used as the arithmetic device 2104 and the control device 2107.

  As another function, by grasping the type and number of products stored in the refrigerator 2102, cooling is weakened when there are not many products in the refrigerator 2102, and conversely strengthened when many products are contained. It becomes possible. Furthermore, cooling can be weakened or strengthened only at a specific position in the refrigerator 2102. In addition, by installing the monitor 2108 in the refrigerator 2102, it is possible to check what is inside without opening the refrigerator 2102.

  Moreover, it is also possible to perform the cooling method according to the goods put in the refrigerator. Whether to cool quickly or slowly is determined according to the information of the wireless IC tag. A control signal is sent to the adjusting device 2106 according to the determination, and the adjusting device 2106 adjusts cooling according to the control signal.

  Thus, by controlling the state in the refrigerator according to the situation, the product can be stored well for a long time, and wasteful power consumption can be reduced. The method of adjusting the temperature is not limited to the method described here.

  In this embodiment, a refrigerator for storing food has been described, but an article that needs to be stored by adjusting temperature, humidity, brightness, etc. (for example, (1) chemical substances and pharmaceuticals, (2) cells, bacteria, etc. A living body such as a plant or an animal, or (3) a living body such as an enzyme or DNA), a wireless IC tag to which information on the product is input is attached to the container, or the wireless IC tag is attached to the sample itself. By doing so, it can be used similarly.

  In the case of a washing machine, it is necessary to set a washing method suitable for washing, the type and amount of detergent, the amount of water used for washing, and the like. In general, since the laundry has various sizes and types, the setting of the laundry is troublesome. In recent years, many washing machines with many functions are on the market, but there are many cases where consumers cannot use the functions of washing machines.

  In the one-tank type dehydrating washing machine that is generally marketed, the weight of the laundry is measured by measuring the power for turning the washing / dehydrating tub after putting the laundry in the washing / dehydrating tub. The amount of water is determined by the weight of the laundry. Therefore, even if it is the same weight, when washing large and bulky items such as sheets and small items such as denim jackets, washing is done in exactly the same way, both in the amount of water and in the washing method. . Since the amount of detergent is set in accordance with the amount of water used for washing, the amount of detergent may not be appropriate in the above case.

  Therefore, as shown in FIG. 23, when the laundry 2301 in which the wireless IC tag 2300 is embedded in the clothing is put into the washing machine 2302, information such as the type, size, weight, and material of the laundry is stored in the washing machine. The attached reader 2303 reads and transmits the information to the arithmetic unit. The arithmetic unit determines an appropriate washing course, the type and amount of detergent, and the amount of water from the information on the laundry. Then, the type and amount of detergent to be input are displayed on a monitor 2304 attached to the washing machine. The consumer can put in the detergent according to the display and press the start button of the washing machine. Thus, after the setting regarding washing is automatically performed, washing is performed.

  Various electronic devices can be completed using TFTs manufactured using the present invention. A specific example will be described with reference to FIG.

  By using the present invention, a laser beam having a uniform intensity can be obtained without generating laser interference fringes on a semiconductor film. By using this laser beam, the entire surface of the semiconductor film can be annealed satisfactorily. Therefore, it is possible to remove restrictions on the layout and size of the semiconductor device and improve the degree of integration. Further, since the crystallinity is the same in any part of the substrate, the product quality of the manufactured semiconductor element is good, and it is possible to eliminate variations in the quality. As a result, an electronic device as a final product can be manufactured with good quality and high throughput. A specific example will be described with reference to the drawings.

  FIG. 24A illustrates a display device, which includes a housing 2401, a support base 2402, a display portion 2403, a speaker portion 2404, a video input terminal 2405, and the like. This display device is manufactured by using a TFT formed by a manufacturing method shown in another embodiment for a driver IC, a display portion 2403, or the like. The display device includes a liquid crystal display device, a light-emitting display device, and the like, and all information display devices such as a computer, a television receiver, and an advertisement display are included depending on the application. Specifically, a display, a head mounted display, a reflective projector, and the like can be given.

  FIG. 24B illustrates a computer, which includes a housing 2411, a display portion 2412, a keyboard 2413, an external connection port 2414, a pointing mouse 2415, and the like. The TFT formed using the present invention can be applied not only to the pixel portion of the display portion 2412 but also to a semiconductor device such as a display driver IC, a CPU in the main body, and a memory.

  FIG. 24C illustrates a mobile phone, which is a typical example of a portable information processing terminal. This mobile phone includes a housing 2421, a display portion 2422, operation keys 2423, and the like. The TFT formed using the present invention can be used not only for the pixel portion of the display portion 2422 and the sensor portion 2424 but also for a display driver IC, a memory, an audio processing circuit, and the like. The sensor unit 2424 includes an optical sensor element, and controls the luminance of the display unit 2422 according to the illuminance obtained by the sensor unit 2424, or controls the illumination of the operation key 2423 according to the illuminance obtained by the sensor unit 2424. By suppressing the power consumption, the power consumption of the mobile phone can be suppressed.

  A semiconductor device formed using the present invention can also be used for electronic devices such as PDAs (Personal Digital Assistants, information portable terminals), digital cameras, and small game machines as well as the above mobile phones. For example, it is possible to form functional circuits such as a CPU, a memory, and a sensor, and to apply to a pixel portion of these electronic devices and a display driver IC.

  24D and 24E are digital cameras. Note that FIG. 24E illustrates the back side of FIG. This digital camera includes a housing 2431, a display portion 2432, a lens 2433, operation keys 2434, a shutter 2435, and the like. The TFT formed using the present invention can be used for a pixel portion of the display portion 2432, a driver IC for driving the display portion 2432, a memory, or the like.

  FIG. 24F illustrates a digital video camera. This digital video camera includes a main body 2441, a display portion 2442, a housing 2443, an external connection port 2444, a remote control receiving portion 2445, an image receiving portion 2446, a battery 2447, an audio input portion 2348, operation keys 2449, an eyepiece portion 2450, and the like. . The TFT formed using the present invention can be used for a pixel portion of the display portion 2342, a driver IC for controlling the display portion 2342, a memory, a digital input processing device, or the like.

  In addition, the present invention can be used for a navigation system, a sound reproducing device, an image reproducing device including a recording medium, and the like. TFTs formed by using the present invention can be used for pixel portions of these display portions, drive ICs that control the display portions, memories, digital input processing devices, sensor portions, and the like.

  As described above, the applicable range of the semiconductor device manufactured according to the present invention is so wide that the semiconductor device manufactured according to the present invention can be used for electronic devices in various fields. Note that a display device used in these electronic devices can use not only a glass substrate but also a heat-resistant synthetic resin substrate depending on the size, strength, or purpose of use. Thereby, further weight reduction can be achieved.

It is a figure which shows the outline | summary of a laser irradiation apparatus. It is a figure explaining the function of the laser irradiation apparatus of FIG. It is a figure which shows the example of a slit. It is a figure which shows the detail of the optical system of a laser irradiation apparatus. It is a figure which shows the detail of the optical system of a laser irradiation apparatus. It is a figure which shows the outline | summary of a laser irradiation apparatus. It is a figure explaining reflection of the light by a mirror. It is a figure explaining reflection of the light by a phase conjugate mirror. It is a figure which shows the detail of the laser irradiation apparatus of this invention using a phase conjugate mirror. It is a figure which shows the detail of the laser irradiation apparatus of this invention using a phase conjugate mirror. It is a figure explaining the positional relationship of the optical system of FIG. It is a figure which shows the preparation processes of a semiconductor element. 10A to 10D illustrate a method for manufacturing a crystalline semiconductor film. 10A to 10D illustrate a method for manufacturing a crystalline semiconductor film. FIG. 6 illustrates a manufacturing process of a semiconductor device. FIG. 6 illustrates a manufacturing process of a semiconductor device. FIG. 6 illustrates a manufacturing process of a semiconductor device. FIG. 6 illustrates a manufacturing process of a semiconductor device. FIG. 6 illustrates a manufacturing process of a semiconductor device. It is the figure which showed the specific usage method of the semiconductor device. It is the figure which showed the specific usage method of the semiconductor device. 3 is a flowchart illustrating an information processing method of a semiconductor device. It is the figure which showed the specific usage method of the semiconductor device. It is a figure showing an example of electronic equipment. It is a figure which shows the relationship between the intensity distribution of a laser beam, and the irradiation trace in a semiconductor film (background art). It is a figure for demonstrating the laser irradiation apparatus using a diffractive optical element (background art).

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Laser oscillator 102 Diffraction optical element 103 Slit 104 Projection lens 105 Condensing lens 106 Mirror 107 Semiconductor film 108 Adsorption stage 109 X stage 110 Y stage 301 Opening part 302 Shielding plate 330 Center wavelength 501 Laser oscillator 502 Diffraction optical element 503 Slit 504 Projection Lens 505 Condensing lens 506 Semiconductor film 507 Correction lens 515 Center wavelength 601 Laser oscillator 602 Diffractive optical element 603 Slit 604 Projection lens 605 Condensing lens 606 Mirror 607 Semiconductor film 608 Adsorption stage 609 X stage 610 Y stage 901 Laser oscillator 902 Diffraction Optical element 903 Slit 904 Beam splitter 905 Semiconductor film 906 Phase conjugate mirror 907 Condensing lens 1000 Laser oscillator 1003 Phase conjugate mirror 1 004 Beam splitter 1005 Diffractive optical element 1006 Slit 1007 Projection lens 1008 Condensing lens 1009 Semiconductor film 1010 X stage 1011 Y stage

Claims (16)

A laser oscillator;
A beam homogenizer for homogenizing the intensity distribution of the laser beam emitted from the laser oscillator;
A slit for blocking the end of the laser beam that has passed through the beam homogenizer;
A projection lens for projecting an image of the slit onto the irradiation surface;
A condensing lens for condensing the image of the slit on the irradiation surface;
Means for moving the irradiation surface relative to the laser beam. In claim 1,
The laser irradiation apparatus, wherein the beam homogenizer is a diffractive optical element. In claim 1 or claim 2,
The laser irradiation apparatus, wherein the projection lens is a convex cylindrical lens or a convex spherical lens. In any one of Claims 1 thru | or 3,
The condensing lens may be a convex cylindrical lens or a convex spherical lens. In any one of Claims 1 thru | or 4,
The width of the opening of the slit is a, the length of the long axis of the laser beam on the irradiation surface is b, the focal length of the projection lens is f, and the first main surface of the projection lens from the surface on the exit side of the slit. When the distance to the point is d ₁ and the distance from the second principal point of the projection lens to the irradiation surface is d ₂ , a, b, f, d ₁ and d ₂ are 1 / f = (1 / d ₁ ) + (1 / d ₂ ), d ₁ : d ₂ = a: b In any one of Claims 1 thru | or 5,
The laser irradiation apparatus, wherein the slit has a shielding plate for adjusting the width of the opening. In any one of Claims 1 thru | or 6,
The laser irradiation apparatus, wherein the laser beam is a continuous wave laser beam or a pulsed laser beam having an oscillation frequency of 10 MHz or more. 8. The laser oscillator according to claim 7, wherein the laser oscillator includes single crystal YAG, YVO ₄ , forsterite, YAlO ₃ , GdVO ₄ , polycrystalline YAG, Y ₂ O ₃ , YVO ₄ , YAlO ₃ , GdVO ₄ , or an optical fiber. In addition, Nd, Yb, Cr, Ti, Ho, Er, Tm, and Ta as a dopant are selected from lasers, Ar ion lasers, or Ti: sapphire lasers that contain one or more of them as a medium. A laser irradiation apparatus which is a laser oscillator. In claim 7 or claim 8,
The laser irradiation apparatus, wherein the laser beam is a harmonic converted by a nonlinear optical element. A laser beam is emitted from a laser oscillator,
Passing the laser beam through a beam homogenizer for uniform intensity distribution;
The laser beam that has passed through the beam homogenizer passes through the slit,
The laser beam that has passed through the slit is passed through a projection lens and a condenser lens,
Irradiate the irradiated surface,
A laser irradiation method comprising irradiating the laser beam while moving the irradiation surface relative to the laser beam. In claim 10,
The width of the opening of the slit is a, the length of the long axis of the laser beam on the irradiation surface is b, the focal length of the projection lens is f, and the first main surface of the projection lens from the surface on the exit side of the slit. If the distance to the point is d ₁ and the distance from the second principal point of the projection lens to the irradiation surface is d ₂ ,
1 / f = (1 / d ₁ ) + (1 / d ₂ )
d ₁ : d ₂ = a: b
The laser irradiation method characterized by having the following relationship. In claim 9 or 11,
The irradiation method, wherein the beam homogenizer is a diffractive optical element. In any one of Claims 9-12,
The laser irradiation method, wherein the projection lens is a convex cylindrical lens or a convex spherical lens. In any one of Claims 10 to 13,
The laser irradiation method, wherein the condenser lens is a convex cylindrical lens or a convex spherical lens. In any one of Claim 9 thru | or Claim 14,
The laser irradiation method, wherein the laser beam is a continuous wave laser or a pulsed laser having an oscillation frequency of 10 MHz or more. In any one of Claim 9 thru | or Claim 14,
The laser beam emitted from the laser oscillator is applied to single crystal YAG, YVO ₄ , forsterite, YAlO ₃ , GdVO ₄ , polycrystalline YAG, Y ₂ O ₃ , YVO ₄ , YAlO ₃ , GdVO ₄ or an optical fiber. A laser, Ar ion laser, or Ti: sapphire laser using a crystal added with one or more of Nd, Yb, Cr, Ti, Ho, Er, Tm, and Ta as a dopant. A laser irradiation method.

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