JP2004200559A - Laser irradiation method and method for manufacturing semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem wherein when a semiconductor film is scanned relatively and is irradiated with a CW laser in the manufacturing process of a semiconductor device, characteristics practically approximate to a single crystal is obtained in the scanning direction, but productivity and uniformity of laser anneal are inferior and massproduction is difficult. <P>SOLUTION: A plurality of laser beams are shaped into a linear beam, and made to approach to each other and are given a overlapped part, thereby forming a longer linear beam and improving the productivity. When positional relation, satisfying a prescribed confinement formula, is imparted to the mutually adjacent linear beams, uniformity of laser annealing is markedly improved. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a laser light irradiation method and a laser irradiation device (a device including a laser oscillation device and an optical system for guiding output laser light to an irradiation target) for performing the method. Further, the present invention relates to a method for manufacturing a semiconductor device including crystallization, activation, heating, or the like of a semiconductor film in a process by irradiation with laser light. Note that the semiconductor device here includes an electro-optical device such as a liquid crystal display device or a light-emitting device, and an electronic device including the electro-optical device as a component.
[0002]
[Prior art]
In recent years, techniques for crystallizing an amorphous semiconductor film formed on an insulating substrate such as glass to form a semiconductor film having a crystal structure (hereinafter, referred to as a crystalline semiconductor film) have been widely studied. As a crystallization method, a thermal annealing method using a furnace annealing furnace, an instantaneous thermal annealing method (RTA method), a laser annealing method, and the like have been studied. At the time of crystallization, it is also possible to carry out any one or a combination of these methods.
[0003]
A crystalline semiconductor film has much higher mobility than an amorphous semiconductor film. Therefore, a thin film transistor (hereinafter, referred to as a TFT) is formed using the crystalline semiconductor film, and a TFT for a pixel portion, or a TFT for a pixel portion and a driver circuit is formed over one glass substrate, for example. Of the active matrix type liquid crystal display device.
[0004]
Usually, in order to crystallize an amorphous semiconductor film in a furnace annealing furnace, a heat treatment at 600 ° C. or more for 10 hours or more is required. The substrate material applicable to this crystallization is quartz, but the quartz substrate is expensive and it is very difficult to process a large area in particular. One of the means for increasing the production efficiency is to increase the area of the substrate, but this is the reason why research on forming a semiconductor film on a glass substrate that is inexpensive and easy to process into a large-area substrate is performed. . In recent years, the use of a glass substrate having a size exceeding 1 m on one side has been considered.
[0005]
As one example, a thermal crystallization method using a metal element has made it possible to lower the crystallization temperature, which has conventionally been regarded as a problem (see, for example, Patent Document 1). According to this method, a trace amount of an element such as nickel, palladium, or lead is added to an amorphous semiconductor film, and then a crystalline semiconductor film can be formed by heat treatment at 550 ° C. for 4 hours. If the temperature is 550 ° C., the temperature is not higher than the strain point temperature of the glass substrate, so that there is no risk of deformation or the like.
[0006]
On the other hand, the laser annealing method can apply high energy only to the semiconductor film without significantly increasing the temperature of the substrate, and thus can be used not only for a glass substrate having a low strain point temperature but also for a plastic substrate or the like. It is a technology that has received attention in this regard.
[0007]
One example of the laser annealing method is to form a pulsed laser beam represented by an excimer laser on an irradiation surface into an optical system so as to form a square spot of several cm square or a linear shape having a length of 100 mm or more. Is performed by moving the irradiation position relative to the irradiation target. Here, the term “linear” does not mean a “line” in a strict sense, but means a rectangle having a large aspect ratio (or a long ellipse or a shape that can be approximated to the rectangle). For example, an aspect ratio of 2 or more (preferably 10 to 10000) refers to a laser beam (rectangular beam) having a rectangular shape on the irradiation surface. Note that the linear shape is used to secure an energy density for performing sufficient annealing on the irradiation target, and sufficient annealing can be performed on the irradiation target even in a rectangular shape or a planar shape. If it is, it does not matter.
[0008]
The crystalline semiconductor film thus manufactured is formed by assembling a plurality of crystal grains, and the positions and sizes of the crystal grains are random. A TFT manufactured on a glass substrate is formed by separating a crystalline semiconductor into island-shaped patterning for element isolation. In that case, it has not been possible to form the crystal grains by specifying the position and size of the crystal grains. Compared with the inside of the crystal grain, the interface (crystal grain boundary) of the crystal grain has a myriad of recombination centers and capture centers due to an amorphous structure, crystal defects, and the like. It is known that, when carriers are trapped in the trapping center, the potential of the crystal grain boundary increases and acts as a barrier to the carriers, so that the current transport characteristics of the carriers are reduced. Although the crystallinity of the semiconductor film in the channel formation region has a significant effect on the characteristics of the TFT, it is almost impossible to form the channel formation region with a single crystal semiconductor film by eliminating the influence of crystal grain boundaries. Was.
[0009]
Recently, a technique has been reported in which a continuous wave (CW) laser irradiates a semiconductor film while scanning it in one direction, thereby growing crystals connected to the scanning direction and forming countless single crystal grains elongated in that direction. (For example, see Non-Patent Document 1).
[0010]
It is considered that by using this method, a TFT having almost no crystal grain boundaries at least in the channel direction of the TFT can be formed.
[0011]
[Patent Document 1]
JP-A-7-183540
[Non-patent document 1]
Hara, 5 others, “Ultra-high Performance Poly-Si TFTs on a Glass by a Stable Scanning CW Laser Lateral Crystallization”, AMLC 01 (AMLCD '01), 2001, p.227-230.
[0012]
[Problems to be solved by the invention]
However, in this method, since a CW laser having a wavelength range sufficiently absorbed by the semiconductor film is used, only a very small laser having an output of about 10 W can be applied. Inferior to comparison. A CW laser suitable for the present method has a high output, a wavelength equal to or lower than that of visible light, and has extremely high output stability._FourThe second harmonic of the laser, the second harmonic of the YAG laser, the second harmonic of the YLF laser, YAlO_ThreeThe second harmonic of a laser, an Ar laser or the like is applicable. However, when the lasers listed above are applied to the crystallization of semiconductor films, it is necessary to significantly reduce the beam spot size in order to compensate for insufficient output. There's a problem. An object of the present invention is to overcome such disadvantages.
[0013]
[Means for Solving the Problems]
In the step of crystallizing a semiconductor film using a CW laser, a laser beam is processed into an elongated shape on an irradiation surface in order to increase productivity at least, and is elongated in a longitudinal direction of the elongated laser beam (hereinafter, referred to as a linear beam). Scanning in a vertical direction to crystallize a semiconductor film is actively performed.
[0014]
The shape of an elongated laser beam is greatly affected by the shape of a laser beam emitted from a laser oscillator. For example, when the shape of the rod used in the solid-state laser is round, the shape of the emitted laser beam is also round, and when it is extended, it becomes an elliptical laser beam, or the rod used in the solid-state laser is Is a slab, the shape of the emitted laser beam is rectangular, and when it is stretched, it becomes a rectangular laser beam. However, in the case of a slab laser, it is necessary to note that the divergence angle differs between the major axis direction and the minor axis direction of the beam, so that the shape of the beam greatly differs depending on the distance from the laser oscillator. In the present invention, these beams are collectively referred to as linear beams. In the present invention, a linear beam refers to a beam whose length in the longitudinal direction is 10 times or more the length in the lateral direction. In the present invention, when the maximum energy density of the linear beam is 1, e^-2The range having the above energy is defined as a linear beam. Further, in this specification, the length of the linear beam is expressed as a major axis, and the width is expressed as a minor axis.
[0015]
In the present invention, a plurality of lasers having a small output are used, each laser beam is shaped into a linear beam, and then a longer linear beam is formed by synthesizing those laser beams, thereby improving productivity and laser annealing. Improve uniformity. Further, the present invention provides a laser irradiation apparatus and a laser irradiation method with a higher degree of uniformity of laser annealing, and a method for manufacturing a semiconductor device, by digitizing the degree of synthesis. The present invention is described below.
[0016]
The configuration related to the laser irradiation method disclosed in the present invention is such that, when a plurality of laser beams emitted from a plurality of laser oscillators have a round shape, a plurality of laser beams are stretched to have a long diameter e.^-2Width a, minor axis e^-2When processing into a linear beam having a width b and overlapping the ends in the major axis direction to form a longer linear beam, the center coordinates of the laser beams overlapping each other among the plurality of laser beams are respectively (x, y), (x ′, y ′), when the major axis and the x axis are extended in parallel and the minor axis and the y axis are extended in parallel,
((Xx ') / a)^Two+ ((Yy ') / b)^Two<(R)^Two
A laser irradiation method that satisfies the following. The above R is 0.72, preferably 0.63. Outside the range of the above inequality, there is a region in which elongated single crystal grains are not formed between adjacent (overlapping) linear beams. The meaning of combining them becomes sparse.
[0017]
Another configuration of the invention related to the laser irradiation method disclosed in the present invention is that when a plurality of laser beams emitted from a plurality of laser oscillators have a rectangular shape, the plurality of laser beams are elongated to have a long diameter e.^-2Width a, minor axis e^-2When processing into a linear beam having a width b and overlapping the ends in the major axis direction to form a longer linear beam, the center coordinates of the laser beams overlapping each other among the plurality of laser beams are respectively (x, y), (x ′, y ′), when the major axis and the x axis are extended in parallel and the minor axis and the y axis are extended in parallel,
| Y−y ′ | / b <R, and | xx ′ | <a
A laser irradiation method that satisfies the following. The above R is 0.72, preferably 0.63. The above inequality shows a Gaussian energy distribution in the minor axis direction, and can be applied to a linear beam having a uniform energy distribution in the major axis direction. Outside the range of the above inequality, there is a region in which elongated single crystal grains are not formed between adjacent (overlapping) linear beams. The meaning of combining them becomes sparse.
[0018]
Another configuration of the invention related to the laser irradiation method disclosed in the present invention is that when a plurality of laser beams emitted from a plurality of laser oscillators have a rectangular shape, the plurality of laser beams are elongated to have a long diameter e.^-2Width a, minor axis e^-2When processing into a linear beam having a width b and overlapping the ends in the major axis direction to form a longer linear beam, the center coordinates of the laser beams overlapping each other among the plurality of laser beams are respectively (x, y), (x ′, y ′), when the major axis and the x axis are extended in parallel and the minor axis and the y axis are extended in parallel,
| Xx ′ | / a <R, and | yy ′ | <b
A laser irradiation method that satisfies the following. The above R is 0.72, preferably 0.63. The above inequality shows a Gaussian energy distribution in the major axis direction, and can be applied to a linear beam having a uniform energy distribution in the minor axis direction. Outside the range of the above inequality, there is a region in which elongated single crystal grains are not formed between adjacent (overlapping) linear beams. The meaning of combining them becomes sparse.
[0019]
Another configuration of the invention related to the laser irradiation method disclosed in the present invention is that, when a plurality of laser beams emitted from a plurality of laser oscillators have a rectangular shape, the plurality of laser beams are extended to have a long diameter e.^-2Width a, minor axis e^-2When processing into a linear beam having a width b and overlapping the ends in the major axis direction to form a longer linear beam, the center coordinates of the mutually overlapping laser beams among the plurality of laser beams are respectively (x, y), (x ′, y ′), when the major axis and the x axis are extended in parallel and the minor axis and the y axis are extended in parallel,
| Xx ′ | / a <R, and | yy ′ | / b <R
A laser irradiation method that satisfies the following. The above R is 0.72, preferably 0.63. The above inequality can be applied to a linear beam having a Gaussian energy distribution in the minor axis direction and a Gaussian energy distribution in the major axis direction. Outside the range of the above inequality, there is a region in which elongated single crystal grains are not formed between adjacent (overlapping) linear beams. The meaning of combining them becomes sparse.
[0020]
Another configuration of the invention related to the laser irradiation method disclosed in the present invention is that, when the shapes of the plurality of laser beams emitted from the plurality of laser oscillators are round and rectangular, the plurality of e^-2Width a, minor axis e^-2When processing into a linear beam having a width b and overlapping the ends in the major axis direction to form a longer linear beam, the center coordinates of the mutually overlapping laser beams among the plurality of laser beams are respectively (x, y), (x ′, y ′), when the major axis and the x axis are extended in parallel and the minor axis and the y axis are extended in parallel,
((Xx ') / a)^Two+ ((Yy ') / b)^Two<(R)^Two
A laser irradiation method that satisfies the following. The above R is 0.72, preferably 0.63. Outside the range of the above inequality, there is a region in which elongated single crystal grains are not formed between adjacent (overlapping) linear beams. The meaning of combining them becomes sparse.
[0021]
In the above invention,
0.52 <| xx ′ | / a
When the value is satisfied, the length of the linear beam can be increased, so that the productivity is increased and this is preferable.
[0022]
In the above invention,
b <[50 μm]
When the value is satisfied, the length of the linear beam can be increased, so that the productivity is increased and this is preferable.
[0023]
In the above structure of the invention, the laser is a continuous wave gas laser, a solid-state laser, or a metal laser. Ar laser, Kr laser, CO_TwoLaser, etc., and solid-state lasers such as YAG laser,_FourLaser, YLF laser, YAlO_ThreeLaser, Y_TwoO_ThreeThere are a laser, a glass laser, a ruby laser, an alexandrite laser, a Ti: sapphire laser, and the like, and examples of the metal laser include a helium cadmium laser, a copper vapor laser, a gold vapor laser, and the like. Excimer lasers are usually pulsed, but there is a theory that continuous oscillation is also possible in principle. If such a thing is made, a continuous wave excimer laser can be applied to the present invention.
[0024]
In the configuration of the invention described above, the laser beam is converted into a harmonic by a nonlinear optical element. The crystal used for the non-linear optical element is excellent in terms of conversion efficiency when using a material called LBO, BBO, KDP, KTP, KB5, or CLBO, for example. By placing these nonlinear optical elements in the laser cavity, the conversion efficiency can be greatly increased.
[0025]
In the configuration of the above invention, the laser beam is a TEM.₀₀Oscillation is preferable because the energy uniformity of the obtained long beam can be improved.
[0026]
The configuration of the invention related to the laser irradiation apparatus disclosed in the present invention includes a plurality of laser oscillators, means for extending a plurality of laser beams emitted from the plurality of laser oscillators, and having a round spot shape, and Means for forming a linear beam on the irradiation surface or in the vicinity thereof, wherein the plurality of laser beams overlap each other in the long diameter direction, and a laser irradiation device comprising: E of the major axis on the irradiated surface of^-2Width a, minor axis e^-2When the width is set to b, the major axis and the x-axis are coordinated in parallel, and the minor axis and the y-axis are coordinated in parallel, the center coordinates of the mutually overlapping laser beams among the plurality of elongated laser beams are (x , Y), (x ', y'),
((Xx ') / a)^Two+ ((Yy ') / b)^Two<R^Two
A laser irradiation apparatus characterized by satisfying the following. The above R is 0.72, preferably 0.63. Outside the range of the above inequality, there is a region in which elongated single crystal grains are not formed between adjacent (overlapping) linear beams. The meaning of combining them becomes sparse.
[0027]
Another configuration of the invention related to the laser irradiation device disclosed in the present invention, a plurality of laser oscillators, and a means for extending a plurality of laser beams emitted from the plurality of laser oscillators and having a rectangular spot shape, Means for superimposing a plurality of elongated laser beams with each other in the long diameter direction to form a linear beam on or near an irradiation surface, comprising: a plurality of elongated laser beams. Of the major axis at each irradiation surface of^-2Width a, minor axis e^-2When the width is set to b, the major axis and the x-axis are coordinated in parallel, and the minor axis and the y-axis are coordinated in parallel, the center coordinates of the mutually overlapping laser beams among the plurality of elongated laser beams are (x , Y), (x ', y'),
| Y−y ′ | / b <R, and | xx ′ | <a
A laser irradiation apparatus characterized by satisfying the following. The above R is 0.72, preferably 0.63. Outside the range of the above inequality, there is a region in which elongated single crystal grains are not formed between adjacent (overlapping) linear beams. The meaning of combining them becomes sparse.
[0028]
Another configuration of the invention related to the laser irradiation device disclosed in the present invention, a plurality of laser oscillators, and a means for extending a plurality of laser beams emitted from the plurality of laser oscillators and having a rectangular spot shape, Means for superimposing a plurality of elongated laser beams with each other in the long diameter direction to form a linear beam on or near an irradiation surface, comprising: a plurality of elongated laser beams. Of the major axis at each irradiation surface of^-2Width a, minor axis e^-2When the width is set to b, the major axis and the x-axis are coordinated in parallel, and the minor axis and the y-axis are coordinated in parallel, the center coordinates of the mutually overlapping laser beams among the plurality of elongated laser beams are (x , Y), (x ', y'),
| Xx ′ | / a <R, and | yy ′ | <b
A laser irradiation apparatus characterized by satisfying the following. The above R is 0.72, preferably 0.63. Outside the range of the above inequality, there is a region in which elongated single crystal grains are not formed between adjacent (overlapping) linear beams. The meaning of combining them becomes sparse.
[0029]
Another configuration of the invention related to the laser irradiation device disclosed in the present invention, a plurality of laser oscillators, and a means for extending a plurality of laser beams emitted from the plurality of laser oscillators and having a rectangular spot shape, Means for superimposing a plurality of elongated laser beams with each other in the long diameter direction to form a linear beam on or near an irradiation surface, comprising: a plurality of elongated laser beams. Of the major axis at each irradiation surface of^-2Width a, minor axis e^-2When the width is set to b, the major axis and the x-axis are coordinated in parallel, and the minor axis and the y-axis are coordinated in parallel, the center coordinates of the mutually overlapping laser beams among the plurality of elongated laser beams are (x , Y), (x ', y'),
| Xx ′ | / a <R, and | yy ′ | / b <R
A laser irradiation apparatus characterized by satisfying the following. The above R is 0.72, preferably 0.63. Outside the range of the above inequality, there is a region in which elongated single crystal grains are not formed between adjacent (overlapping) linear beams. The meaning of combining them becomes sparse.
[0030]
Another configuration of the invention related to the laser irradiation apparatus disclosed in the present invention includes a plurality of laser oscillators and a plurality of laser oscillators which are emitted from the plurality of laser oscillators, and whose cross-sectional shapes perpendicular to the traveling direction are round and rectangular. Means for stretching the laser beam, means for extending the plurality of stretched laser beams with each other in the longitudinal direction, forming a linear beam on the irradiation surface or in the vicinity thereof, and means for stretching the plurality of laser beams. E of the major axis on each irradiation surface^-2Width a, minor axis e^-2When the width is set to b, the major axis and the x-axis are coordinated in parallel, and the minor axis and the y-axis are coordinated in parallel, the center coordinates of the mutually overlapping laser beams among the plurality of elongated laser beams are (x , Y), (x ', y'),
((Xx ') / a)^Two+ ((Yy ') / b)^Two<R^Two
A laser irradiation apparatus characterized by satisfying the following. The above R is 0.72, preferably 0.63. Outside the range of the above inequality, there is a region in which elongated single crystal grains are not formed between adjacent (overlapping) linear beams. The significance of combining them becomes less.
[0031]
The structure of the invention relating to the method for manufacturing a semiconductor device disclosed in the present invention is that a plurality of laser beams are processed into a plurality of linear beams on or near a semiconductor film, and a plurality of laser beams emitted from a plurality of laser oscillators are processed. In the case where the shape of the laser beam is round, a plurality of laser beams are irradiated on the semiconductor film or in the vicinity of the semiconductor film with a long diameter e.^-2Width a, minor axis e^-2When processing into a linear beam having a width b and overlapping the ends in the major axis direction to form a longer linear beam, the center coordinates of the laser beams overlapping each other among the plurality of laser beams are respectively (x, y), (x ′, y ′), when the major axis and the x axis are extended in parallel and the minor axis and the y axis are extended in parallel,
((Xx ') / a)^Two+ ((Yy ') / b)^Two<(R)^Two
A method for manufacturing a semiconductor device that satisfies the following conditions. The above R is 0.72, preferably 0.63. Outside the range of the above inequality, there is a region in which elongated single crystal grains are not formed between adjacent (overlapping) linear beams. The meaning of combining them becomes sparse.
[0032]
Another structure of the invention related to the method for manufacturing a semiconductor device disclosed in the present invention is that a plurality of laser beams are processed into a plurality of linear beams on or near a semiconductor film, and a plurality of linear beams emitted from a plurality of laser oscillators are processed. In the case where the shape of the laser beam is rectangular, a plurality of laser beams are irradiated on the semiconductor film or in the vicinity thereof with a long diameter e.^-2Width a, minor axis e^-2When processing into a linear beam having a width b and overlapping the ends in the major axis direction to form a longer linear beam, the center coordinates of the laser beams overlapping each other among the plurality of laser beams are respectively (x, y), (x ′, y ′), when the major axis and the x axis are extended in parallel and the minor axis and the y axis are extended in parallel,
| Y−y ′ | / b <R, and | xx ′ | <a
A method for manufacturing a semiconductor device that satisfies the following conditions. The above R is 0.72, preferably 0.63. Outside the range of the above inequality, there is a region in which elongated single crystal grains are not formed between adjacent (overlapping) linear beams. The meaning of combining them becomes sparse.
[0033]
Another structure of the invention related to the method for manufacturing a semiconductor device disclosed in the present invention is that a plurality of laser beams are processed into a plurality of linear beams on or near a semiconductor film, and a plurality of linear beams emitted from a plurality of laser oscillators are processed. In the case where the shape of the laser beam is rectangular, a plurality of laser beams are irradiated on the semiconductor film or in the vicinity thereof with a long diameter e.^-2Width a, minor axis e^-2When processing into a linear beam having a width b and overlapping the ends in the major axis direction to form a longer linear beam, the center coordinates of the laser beams overlapping each other among the plurality of laser beams are respectively (x, y), (x ′, y ′), when the major axis and the x axis are extended in parallel and the minor axis and the y axis are extended in parallel,
| Xx ′ | / a <R, and | yy ′ | <b
A method for manufacturing a semiconductor device that satisfies the following conditions. The above R is 0.72, preferably 0.63. Outside the range of the above inequality, there is a region in which elongated single crystal grains are not formed between adjacent (overlapping) linear beams. The meaning of combining them becomes sparse.
[0034]
Another structure of the invention related to the method for manufacturing a semiconductor device disclosed in the present invention is that a plurality of laser beams are processed into a plurality of linear beams on or near a semiconductor film, and a plurality of linear beams emitted from a plurality of laser oscillators are processed. When the shape of the laser beam is rectangular, a plurality of laser beams are irradiated on the semiconductor film or in the vicinity of the semiconductor film with a long diameter e.^-2Width a, minor axis e^-2When processing into a linear beam having a width b and overlapping the ends in the major axis direction to form a longer linear beam, the center coordinates of the mutually overlapping laser beams among the plurality of laser beams are respectively (x, y), (x ′, y ′), when the major axis and the x axis are extended in parallel and the minor axis and the y axis are extended in parallel,
| Xx ′ | / a <R, and | yy ′ | / b <R
A method for manufacturing a semiconductor device that satisfies the following conditions. The above R is 0.72, preferably 0.63. Outside the range of the above inequality, there is a region in which elongated single crystal grains are not formed between adjacent (overlapping) linear beams. The meaning of combining them becomes sparse.
[0035]
Another structure of the invention related to the method for manufacturing a semiconductor device disclosed in the present invention is that a plurality of laser beams are processed into a plurality of linear beams on or near a semiconductor film, and a plurality of linear beams emitted from a plurality of laser oscillators are processed. When the laser beam has a round shape and a rectangular shape, a plurality of laser beams are irradiated on the semiconductor film or in the vicinity of the semiconductor film with a long diameter e.^-2Width a, minor axis e^-2When processing into a linear beam having a width b and overlapping the ends in the major axis direction to form a longer linear beam, the center coordinates of the mutually overlapping laser beams among the plurality of laser beams are respectively (x, y), (x ′, y ′), when the major axis and the x axis are extended in parallel and the minor axis and the y axis are extended in parallel,
((Xx ') / a)^Two+ ((Yy ') / b)^Two<(R)^Two
A method for manufacturing a semiconductor device that satisfies the following conditions. The above R is 0.72, preferably 0.63. Outside the range of the above inequality, there is a region in which elongated single crystal grains are not formed between adjacent (overlapping) linear beams. The meaning of combining them becomes sparse.
[0036]
In the above invention,
0.52 <| xx ′ | / a
When the value is satisfied, the linear beam can be made longer, which is preferable because the productivity is increased.
[0037]
In the above structure of the invention, the laser is a continuous wave gas laser, a solid-state laser, or a metal laser. Ar laser, Kr laser, CO_TwoLaser, etc., and solid-state lasers such as YAG laser,_FourLaser, YLF laser, YAlO_ThreeThere are a laser, a glass laser, a ruby laser, an alexandrite laser, a Ti: sapphire laser, and the like, and examples of the metal laser include a helium cadmium laser, a copper vapor laser, a gold vapor laser, and the like. Excimer lasers are usually pulsed, but there is a theory that continuous oscillation is also possible in principle. If such a thing is made, a continuous wave excimer laser can be applied to the present invention.
[0038]
In the configuration of the invention described above, the laser beam is converted into a harmonic by a nonlinear optical element. The crystal used for the non-linear optical element is excellent in terms of conversion efficiency when using a material called LBO, BBO, KDP, KTP, KB5, or CLBO, for example. By placing these nonlinear optical elements in the laser cavity, the conversion efficiency can be greatly increased.
[0039]
In the configuration of the above invention, the laser beam is a TEM.₀₀Oscillation is preferable because the energy uniformity of the obtained long beam can be improved.
[0040]
Further, in this specification, that the energy distribution has a Gaussian shape means that the energy profile of the laser beam on the irradiation surface has a Gaussian distribution or a shape similar thereto.
[0041]
By irradiating the semiconductor film with a plurality of laser beams satisfying the above formula of the present invention, more uniform laser annealing can be performed. The present invention is particularly suitable for crystallization and improvement of crystallinity of a semiconductor film and activation of an impurity element. Further, since a plurality of linear beams are combined with each other, it is possible to improve the throughput. In a semiconductor device typified by an active matrix liquid crystal display device using the present invention, it is possible to improve the operation characteristics and reliability of the semiconductor device. Furthermore, since a solid-state laser can be used instead of using a gas laser as in the conventional laser annealing method, the manufacturing cost of a semiconductor device can be reduced.
[0042]
BEST MODE FOR CARRYING OUT THE INVENTION
(Embodiment 1)
This embodiment will be described with reference to FIGS. 1 to 4, 6, and 7. In the present embodiment, a condition is derived in which a plurality of linear beams are superimposed on each other to form a longer linear beam so that the semiconductor film can be uniformly laser-annealed.
[0043]
First, conditions for laser output for uniformly irradiating the semiconductor film were calculated. In FIG. 4, an LD-pumped 10 W laser oscillator 100 (Nd: YVO) is used._FourLaser, CW, second harmonic). Laser oscillator is TEM₀₀In the oscillation mode, the resonator has a built-in LBO crystal and is converted to the second harmonic. The beam diameter is 2.25 mm. The spread angle is about 0.3 mrad. The traveling direction of the laser beam is converted downward by a 45 ° reflecting mirror inclined 20 ° from the vertical direction. Next, in order to set the major axis of the linear beam 103 to about 250 μm on the surface 104 of the semiconductor film disposed on the horizontal plane and to set the minor axis to about 40 μm, the laser beam is directed to the plano-convex lens 102 having a focal length of 20 mm by an angle of 20 °. Incident. At this time, the plane of the plano-convex lens 102 is made to coincide with the horizontal plane. In this way, a beam that extends long due to astigmatism is formed on the semiconductor film 104. The distance between the plano-convex lens 102 and the semiconductor film 104 was adjusted at a pitch of 100 μm. By this adjustment, a linear beam 103 long in the direction of the intersection of the incident surface and the semiconductor film 104 was formed. The positional relationship between the lens and the semiconductor film is based on a horizontal plane or a vertical direction for the sake of simplicity, but it goes without saying that the present invention can be implemented without any problem if the relative positions are the same.
[0044]
The semiconductor film 104 was formed over a substrate. Specifically, a silicon oxide film having a thickness of about 200 nm was formed on a glass substrate, and an a-Si film having a thickness of 150 nm was further formed thereon. After that, heat treatment was performed for 1 hour in a nitrogen atmosphere at 500 ° C. in order to increase the laser resistance of the semiconductor film.
[0045]
FIG. 3 shows the relationship between the change in the semiconductor film and the laser output when the semiconductor film is annealed by scanning the semiconductor film 104 with the linear beam 103 in the minor axis direction. The horizontal axis in the drawing indicates the major axis direction of the beam, and the vertical axis indicates the output of the laser oscillator. The curve showing the Gaussian distribution in the figure shows the energy distribution in the major axis direction of the linear beam. The scanning speed was fixed at 50 cm / s, the laser output was changed from 3.2 W to 6.2 W, and the state of change of the semiconductor film was observed. When the laser output was 3.2 W or less, the long single crystal grains described above were not formed at all. When the laser output reached 3.7 W, a number of long single crystal grains were formed over a width of about 40 μm. A region covered with long single crystal grains is referred to as a large grain crystal formation region. Similarly, as the laser output was increased to 5.2 W and 6.2 W, the width was increased to 100 μm and 120 μm. When the laser output was increased to 6.2 W, the semiconductor film jumped at the center of the laser beam having the highest laser output. The width of the region where the semiconductor film has jumped was about 20 μm. From the above results, in FIG. 3, the range of the laser output in which the large grain size crystal forming region can be formed can be specified. That is, the long horizontal line A in the center of FIG. 3 represents the threshold value of the laser output in which a large grain size crystal formation region is formed, and the long horizontal line B above the laser output threshold value at which the semiconductor film flies and becomes unusable. Indicates a threshold.
[0046]
It can be seen from this experimental result that if the maximum value of energy in the energy distribution of the cross section in the minor axis direction of the linear beam forms a linear beam between the line A and the line B, the linear beam A large grain size crystal forming region which spreads uniformly in the major axis direction is obtained. If there is an energy distribution exceeding the line B in the major axis direction of the linear beam, the semiconductor film jumps and uniform laser annealing cannot be performed. If the energy distribution below the line A in the major axis direction of the linear beam is located at a position dividing the major axis direction of the linear beam, a microcrystalline region or a crystallized region is formed between the two large grain size crystal forming regions. Again, non-crystallized regions are created, which also prevents uniform laser annealing.
[0047]
In order to combine multiple linear beams to form a longer linear beam and perform uniform laser annealing, the energy distribution of the combined linear beam is between line A and line B. There is a need. In terms of numerical values, there is a laser output capable of performing uniform laser annealing if the energy distribution is within ± 25%. This will be described with reference to FIGS.
[0048]
FIG. 1 shows a state in which two linear beams are adjacent to each other and are superimposed. The energy distribution of the cross section A-A 'at the center of the linear beam 1 is shown in 1) of FIG. In addition, the energy distribution of the cross section B-B 'between the linear beams 1 and 2 is shown in 2) of FIG. If the maximum energy in each section is E1, E2
| E1-E2 | / | E1 + E2 | ≦ 0.25 ・ ・ ・ 1)
This means that uniform laser annealing can be performed. However, under these conditions, the margin of energy is very small, so if you look at safety,
| E1-E2 | / | E1 + E2 | ≤0.10 ... 2)
If so, uniform laser annealing can be performed more reliably.
[0049]
FIG. 6 shows the result of calculating how much the center-to-center distance between two adjacent linear beams can satisfy the condition satisfying the expression (1) or (2). The graph shown in FIG. 6 shows the difference between the energies E1 and E2 when the offset amount is set to 0 in FIG. That is, the vertical axis is | E1−E2 | / | E1 + E2 | × 100 (%). From the graph of FIG. 6, the center-to-center distance between two linear beams satisfying the expression 1) is within 0.72, and the one satisfying the expression 2) is within 0.63. Become.
[0050]
FIG. 7 shows the relationship between the offset amount and the distance between the two beam centers. If the relationship between the two beams falls within the range within the circle in the figure, the difference between the energies E1 and E2 falls within ± 10%. Similarly, if a circle having a radius of 0.72 is drawn in FIG. 7, if the relationship between the two beams falls within the range of the circle, the difference between the energies E1 and E2 falls within ± 25%. The inequalities indicating the ranges are described in [Means for Solving the Problems]. To describe the inequality again,
((Xx ') / a)^Two+ ((Yy ') / b)^Two<(R)^Two
Becomes However, R is 0.63 or 0.72.
[0051]
Here, the distance is e of the major axis of the linear beam.^-2Standardized by width. When the center-to-center distance is 0.52 or less, the energy difference between E1 and E2 becomes 0, and it is unreasonable to bring the two beams closer to each other because it only shortens the length of the linear beam. Therefore, the center-to-center distance is preferably 0.52 or more.
[0052]
By irradiating a semiconductor film with a plurality of linear beams satisfying the above-described formula of the present invention, more uniform laser annealing can be performed. The present invention is particularly suitable for crystallization and improvement of crystallinity of a semiconductor film and activation of an impurity element. Further, by combining and optimizing a part of the plurality of linear beams, a uniform laser beam can be formed in the major axis direction, so that the throughput can be improved. Then, by crystallization using the highly uniform laser beam, a highly uniform crystalline semiconductor film can be formed, and variation in electrical characteristics of the TFT can be reduced. Furthermore, in a semiconductor device typified by an active matrix liquid crystal display device using the present invention, it is possible to improve the operating characteristics and reliability of the semiconductor device. In addition, since a solid-state laser can be used instead of using a gas laser as in the conventional laser annealing method, a reduction in the manufacturing cost of a semiconductor device can be realized.
[0053]
(Embodiment 2)
In this embodiment, an example is shown in which four lasers are combined to form a longer linear beam. In addition, an example in which a semiconductor film is laser-annealed using the apparatus will be described.
[0054]
First, a method of forming a long linear beam using four laser oscillators will be described with reference to FIG. Cylindrical lenses 201 and 202 are plano-convex cylindrical lenses having a focal length of 20 mm. The generating lines are arranged in parallel to each other, and are symmetrical with respect to a plane perpendicular to the plane 200 including the major axis of the linear beam on the plane 200 where the linear beam is formed. Deploy. The curved surface of the cylindrical lens faces upward. At this time, the generatrix is parallel to the major axis. The cylindrical lenses 201 and 202 are arranged at an angle of 25 ° with respect to the surface 200. The reason for tilting the cylindrical lens in this way is to form four linear beams, which are extremely small as compared with the optical element, on the irradiation surface 200.
[0055]
Plano-convex cylindrical lenses 203 and 205 having a focal length of 150 mm are arranged on a plane perpendicular to the plane part of the cylindrical lens 201 and including the major axis of the linear beam so as to include the optical axis A and the optical axis B. The angle between the optical axis A and the major axis is 80 °, and the angle between the optical axis B and the major axis is also 80 °. The plane part of the cylindrical lens 203 and the optical axis A are perpendicular to each other. Make B vertical. Further, the optical path length of the laser beam emitted from the cylindrical lenses 203 and 205 to the irradiation surface 200 may be set to about 120 mm. At this time, the generatrix of the cylindrical lenses 203 and 205 and the major axis direction of the linear beam are arranged to be perpendicular.
[0056]
The cylindrical lenses 206 and 204 are arranged at positions that are plane-symmetric with respect to the cylindrical lenses 205 and 203, and each have a focal length of 150 mm. The plane is a plane including the major axis of the linear beam and perpendicular to the plane 200. When four laser beams passing through the optical axes A, B, C, and D enter such an optical system, a linear beam 207 shown in an enlarged view in FIG. 5 can be formed. The degree of overlap of these linear beams is synthesized according to the mathematical formula shown in the first embodiment.
[0057]
Next, an example of a method for manufacturing a semiconductor film is described. The semiconductor film is formed over a glass substrate. For example, a 200-nm-thick silicon oxynitride film is formed on one surface of a glass substrate having a thickness of 0.7 mm, and an a-Si film having a thickness of 150 nm is formed thereover by a plasma CVD method. In order to further increase the resistance of the semiconductor film to laser, thermal annealing at 500 ° C. for one hour was performed on the semiconductor film. In addition to the thermal annealing, the semiconductor film may be crystallized with the metal element described in the section of the related art. Regardless of which film is used, the optimum laser beam irradiation conditions are almost the same.
[0058]
Next, an example of laser irradiation on a semiconductor film will be described. The output of each of the four laser oscillators (not shown) is about 10 W at the maximum. These are adjusted to an output suitable for laser annealing. It is preferably about 3 W to 10 W, and the optimum output varies depending on the speed at which the semiconductor film is scanned. The surface of the semiconductor film is placed at the position of the surface 200, and is placed on an appropriate stage and scanned in a direction perpendicular to the major axis of the linear beam 207. Here, when the output is 5 W and the scanning speed is about 50 cm / s, a large grain size crystal forming region having a width of about 1 to 2 mm can be formed. In the case where the area of the surface of the semiconductor film is large, a large grain crystal formation region having a width of 1 to 2 mm is formed in parallel, so that the entire surface of the semiconductor film can be a large grain crystal formation region.
[0059]
As described above, when a plurality of laser beams are synthesized according to the mathematical formulas described in Embodiment Mode 1, and the semiconductor film is irradiated with the synthesized laser beam, more uniform laser annealing can be performed. The present invention is particularly suitable for crystallization and improvement of crystallinity of a semiconductor film and activation of an impurity element. In addition, by combining and optimizing a part of the plurality of linear beams, a uniform laser beam can be formed in the major axis direction, so that the throughput can be improved. Then, by crystallization using the highly uniform laser beam, a highly uniform crystalline semiconductor film can be formed, and variation in electrical characteristics of the TFT can be reduced. Furthermore, in a semiconductor device typified by an active matrix liquid crystal display device manufactured by utilizing the present invention, it is possible to realize improvement in operation characteristics and reliability of the semiconductor device. In addition, since a solid-state laser can be used instead of using a gas laser as in the conventional laser annealing method, a reduction in the manufacturing cost of a semiconductor device can be realized.
[0060]
【Example】
[Example 1]
In this embodiment, a method for manufacturing an active matrix substrate will be described with reference to FIGS. In this specification, a substrate in which a CMOS circuit, a driver circuit, a pixel portion having a pixel TFT, and a storage capacitor are formed over the same substrate is referred to as an active matrix substrate for convenience.
[0061]
First, in this embodiment, a substrate 400 made of glass such as barium borosilicate glass or aluminoborosilicate glass is used. Note that as the substrate 400, a quartz substrate, a silicon substrate, a metal substrate, or a stainless steel substrate on which an insulating film is formed may be used. Further, a plastic substrate having heat resistance enough to withstand the processing temperature of this embodiment may be used, or a flexible substrate may be used. In the present invention, since a linear beam having the same energy distribution can be easily formed, a large-area substrate can be efficiently annealed by a plurality of linear beams.
[0062]
Next, a base film 401 made of an insulating film such as a silicon oxide film, a silicon nitride film, or a silicon oxynitride film is formed over the substrate 400 by a known means. Although a two-layer structure is used as the base film 401 in this embodiment, a single-layer insulating film or a structure in which two or more insulating films are stacked may be used.
[0063]
Next, a semiconductor film is formed over the base film. The semiconductor film is formed to a thickness of 25 to 200 nm (preferably 30 to 150 nm) by a known means (sputtering method, LPCVD method, plasma CVD method, or the like), and is crystallized by a laser crystallization method. In the laser crystallization method, a semiconductor film is irradiated with laser light in Embodiment 1 or Embodiment 2 or a combination of these embodiments. The laser to be used is preferably a continuous wave solid-state laser, gas laser or metal laser. As the solid-state laser, a continuous oscillation YAG laser, YVO_FourLaser, YLF laser, YAlO_ThreeLasers, glass lasers, ruby lasers, alexandrite lasers, Ti: sapphire lasers, etc., and gas lasers such as Ar laser, Kr laser, CO_TwoThere are lasers and the like, and examples of the metal laser include a continuous-wave helium-cadmium laser, a copper vapor laser, and a gold vapor laser. If practical, a continuous wave excimer laser can be applied to the present invention. Of course, in addition to the laser crystallization method, a combination with other known crystallization methods (a thermal crystallization method using an RTA or a furnace annealing furnace, a thermal crystallization method using a metal element that promotes crystallization, and the like). May go. Examples of the semiconductor film include an amorphous semiconductor film, a microcrystalline semiconductor film, and a crystalline semiconductor film. A compound semiconductor film having an amorphous structure such as an amorphous silicon germanium film and an amorphous silicon carbide film is used. May be applied.
[0064]
In this embodiment, an amorphous silicon film having a thickness of 50 nm is formed by a plasma CVD method, and a thermal crystallization method and a laser crystallization method using a metal element which promotes crystallization are performed on the amorphous silicon film. Do. After nickel is used as a metal element and introduced on the amorphous silicon film by a solution coating method, a heat treatment is performed at 550 ° C. for 5 hours to obtain a first crystalline silicon film. And a continuous oscillation YVO with an output of 10 W_FourAfter the laser light emitted from the laser is converted into a second harmonic by a non-linear optical element, laser annealing is performed according to the first embodiment to obtain a second crystalline silicon film. By irradiating the first crystalline silicon film with laser light to form a second crystalline silicon film, crystallinity is improved. The energy density at this time is 0.01 to 100 MW / cm^TwoDegree (preferably 0.1 to 10 MW / cm^Two)is necessary. Then, the stage is relatively moved with respect to the laser beam at a speed of about 0.5 to 2000 cm / s to perform irradiation, thereby forming a second crystalline silicon film.
[0065]
Needless to say, a TFT can be manufactured using the first crystalline silicon film; however, the second crystalline silicon film has improved crystallinity, which is preferable because the electrical characteristics of the TFT are improved.
[0066]
The semiconductor layers 402 to 406 are formed by patterning the crystalline semiconductor film obtained as described above using a photolithography method.
[0067]
After the formation of the semiconductor layers 402 to 406, doping of a slight amount of an impurity element (boron or phosphorus) may be performed in order to control the threshold value of the TFT.
[0068]
Next, a gate insulating film 407 which covers the semiconductor layers 402 to 406 is formed. The gate insulating film 407 is formed of an insulating film containing silicon with a thickness of 40 to 150 nm by a plasma CVD method or a sputtering method. In this embodiment, a silicon oxynitride film is formed with a thickness of 110 nm by a plasma CVD method. Needless to say, the gate insulating film is not limited to the silicon oxynitride film, and another insulating film may be used as a single layer or a stacked structure.
[0069]
Next, a first conductive film 408 having a thickness of 20 to 100 nm and a second conductive film 409 having a thickness of 100 to 400 nm are formed over the gate insulating film 407. In this embodiment, a first conductive film 408 made of a TaN film having a thickness of 30 nm and a second conductive film 409 made of a W film having a thickness of 370 nm are formed by lamination. The TaN film is formed by a sputtering method, and is sputtered using a Ta target in an atmosphere containing nitrogen. The W film was formed by a sputtering method using a W target. In addition, tungsten hexafluoride (WF₆) Can be formed by a thermal CVD method. In any case, it is necessary to reduce the resistance in order to use it as a gate electrode, and it is desirable that the resistivity of the W film be 20 μΩcm or less.
[0070]
In this embodiment, the first conductive film 408 is TaN and the second conductive film 409 is W. However, the present invention is not particularly limited, and any of them is Ta, W, Ti, Mo, Al, Cu, Cr, and Nd. Or an alloy material or a compound material containing the element as a main component. Alternatively, a semiconductor film typified by a polycrystalline silicon film doped with an impurity element such as phosphorus may be used. Further, an AgPdCu alloy may be used.
[0071]
Next, masks 410 to 415 made of resist are formed by photolithography, and a first etching process for forming electrodes and wirings is performed. The first etching process is performed under the first and second etching conditions (FIG. 8B). In this embodiment, an ICP (Inductively Coupled Plasma) etching method is used as a first etching condition, and CF is used as an etching gas._FourAnd Cl_TwoAnd O_TwoThe gas flow ratio is set to 25:25:10 (sccm), and 500 W RF (13.56 MHz) power is applied to the coil-type electrode at a pressure of 1 Pa to generate plasma to perform etching. A 150 W RF (13.56 MHz) power is also applied to the substrate side (sample stage), and a substantially negative self-bias voltage is applied. The W film is etched under the first etching conditions to make the end of the first conductive layer tapered.
[0072]
Thereafter, the second etching condition is changed without removing the resist masks 410 to 415, and the etching gas is CF._FourAnd Cl_TwoAnd a gas flow ratio of 30:30 (sccm), a 500 W RF (13.56 MHz) power is applied to the coil-type electrode at a pressure of 1 Pa to generate plasma, and etching is performed for about 30 seconds. I do. 20 W RF (13.56 MHz) power is also applied to the substrate side (sample stage), and a substantially negative self-bias voltage is applied. CF_FourAnd Cl_TwoUnder the second etching condition in which W is mixed, the W film and the TaN film are etched to the same extent. Note that in order to perform etching without leaving a residue on the gate insulating film, the etching time may be increased by about 10 to 20%.
[0073]
In the first etching process, the shape of the resist mask is made appropriate, so that the edges of the first conductive layer and the second conductive layer are tapered due to the effect of the bias voltage applied to the substrate side. It becomes. The angle of the tapered portion is 15 to 45 °. Thus, the first shape conductive layers 417 to 422 (the first conductive layers 417 a to 422 a and the second conductive layers 417 b to 422 b) composed of the first conductive layer and the second conductive layer by the first etching process. To form Reference numeral 416 denotes a gate insulating film. A region which is not covered with the first shape conductive layers 417 to 422 is etched to a thickness of about 20 to 50 nm to form a thinned region.
[0074]
Next, a second etching process is performed without removing the resist mask. (FIG. 8C) Here, CF is used as the etching gas._FourAnd Cl_TwoAnd O_TwoIs used to selectively etch the W film. At this time, second conductive layers 428b to 433b are formed by a second etching process. On the other hand, the first conductive layers 417a to 422a are hardly etched to form second shape conductive layers 428 to 433.
[0075]
Then, a first doping process is performed without removing the mask made of resist, and an impurity element imparting n-type is added to the semiconductor layer at a low concentration. The doping treatment may be performed by an ion doping method or an ion implantation method. The conditions of the ion doping method are as follows:¹³~ 5 × 10¹⁴/ Cm^TwoAnd an acceleration voltage of 40 to 80 keV. In this embodiment, the dose amount is 1.5 × 10¹³/ Cm^TwoAnd an acceleration voltage of 60 keV. As an impurity element imparting n-type, an element belonging to Group 15 of the periodic table, typically, phosphorus (P) or arsenic (As) is used. Here, phosphorus (P) is used. In this case, conductive layers 428 to 433 serve as a mask for the impurity element imparting n-type, and impurity regions 423 to 427 are formed in a self-aligned manner. 1 × 10 in impurity regions 423 to 427¹⁸~ 1 × 10²⁰/cm^ThreeIs added within the concentration range of n.
[0076]
After removing the resist mask, masks 434a to 434c are newly formed, and the second doping process is performed at an acceleration voltage higher than that of the first doping process. The conditions of the ion doping method are as follows:¹³~ 1 × 10^Fifteen/cm^TwoAnd an acceleration voltage of 60 to 120 keV. In the doping process, the second conductive layers 428b, 430b, and 432b are used as masks for the impurity element, and doping is performed so that the impurity element is added to the semiconductor layer below the tapered portion of the first conductive layer. Subsequently, a third doping process is performed by lowering the acceleration voltage from the second doping process to obtain the state in FIG. The conditions of the ion doping method are as follows:^Fifteen~ 1 × 10¹⁷/cm^TwoAnd an acceleration voltage of 50 to 100 keV. Due to the second doping process and the third doping process, the low-concentration impurity regions 436, 442, and 448 overlapping with the first conductive layer have 1 × 10¹⁸~ 5 × 10¹⁹/cm^ThreeIs added to the high concentration impurity regions 435, 441, 444, and 447.¹⁹~ 5 × 10^{twenty one}/cm^ThreeIs added within the concentration range of n.
[0077]
Needless to say, by setting an appropriate acceleration voltage, the second doping process and the third doping process can form a low-concentration impurity region and a high-concentration impurity region by one doping process.
[0078]
Next, after removing the resist mask, masks 450a to 450c are newly formed and a fourth doping process is performed. By the fourth doping treatment, impurity regions 453, 454, 459, and 460 in which an impurity element imparting a conductivity type opposite to one conductivity type is added to a semiconductor layer to be an active layer of a p-channel TFT are formed. . Using the second conductive layers 429a and 432a as a mask for the impurity element, an impurity element imparting p-type is added to form an impurity region in a self-aligned manner. In this embodiment, the impurity regions 453, 454, 459, and 460 are formed of diborane (B_TwoH₆) (FIG. 9B). In the fourth doping process, the semiconductor layers forming the n-channel TFT are covered with resist masks 450a to 450c. Phosphorus is added at different concentrations to the impurity regions 439, 447, and 448 by the first to third doping processes, and the concentration of the impurity element imparting p-type is set to 1 × 10¹⁹~ 5 × 10^{twenty one}atoms / cm^ThreeBy performing the doping process so as to satisfy the above, there is no problem because it functions as the source region and the drain region of the p-channel TFT.
[0079]
Through the above steps, impurity regions are formed in the respective semiconductor layers.
[0080]
Next, the first interlayer insulating film 461 is formed by removing the resist masks 450a to 450c. The first interlayer insulating film 461 is formed of an insulating film containing silicon with a thickness of 100 to 200 nm by a plasma CVD method or a sputtering method. In this embodiment, a 150-nm-thick silicon oxynitride film is formed by a plasma CVD method. Needless to say, the first interlayer insulating film 461 is not limited to a silicon oxynitride film, and another insulating film containing silicon may be used as a single layer or a stacked structure.
[0081]
Next, for example, irradiation with laser light is performed to recover the crystallinity of the semiconductor layers and activate the impurity elements added to the respective semiconductor layers. In the laser activation, for example, the semiconductor film is irradiated with laser light by using the first or second embodiment or a combination of these embodiments. The laser to be used is preferably a continuous wave solid-state laser, gas laser or metal laser. As the solid-state laser, a continuous oscillation YAG laser, YVO_FourLaser, YLF laser, YAlO_ThreeLasers, glass lasers, ruby lasers, alexandrite lasers, Ti: sapphire lasers, etc., and gas lasers such as Ar laser, Kr laser, CO_TwoThere are lasers and the like, and examples of the metal laser include a continuous-wave helium-cadmium laser, a copper vapor laser, and a gold vapor laser. If practical, a continuous wave excimer laser can be applied to the present invention. At this time, if a continuous wave laser is used, the energy density of the laser beam is 0.01 to 100 MW / cm.^TwoDegree (preferably 0.01 to 10 MW / cm^Two) Is required, and the substrate is moved at a speed of 0.5 to 2000 cm / s relative to the laser beam. In the case of activation, a pulsed laser may be used. In this case, the frequency is set to 300 Hz or more, and the laser energy density is set to 50 to 1000 mJ / cm.^Two(Typically 50-500mJ / cm^Two) Is desirable. At this time, the laser beams may be overlapped by 50 to 98%. Note that, in addition to the laser annealing method, a thermal annealing method, a rapid thermal annealing method (RTA method), or the like can be applied.
[0082]
Further, activation may be performed before forming the first interlayer insulating film. However, when the wiring material used is weak to heat, an active layer is formed after forming an interlayer insulating film (an insulating film containing silicon as a main component, for example, a silicon nitride film) to protect the wiring and the like as in this embodiment. It is preferable to carry out a chemical treatment.
[0083]
Then, when heat treatment (heat treatment at 300 to 550 ° C. for 1 to 12 hours) is performed, hydrogenation can be performed. In this step, dangling bonds in the semiconductor layer are terminated by hydrogen contained in the first interlayer insulating film 461. The semiconductor layer can be hydrogenated regardless of the presence of the first interlayer insulating film.
[0084]
Next, a second interlayer insulating film 462 made of an inorganic insulating material or an organic insulating material is formed over the first interlayer insulating film 461. In the present embodiment, an acrylic resin film having a thickness of 1.6 μm was formed. However, an acrylic resin film having a viscosity of 10 to 1000 cp, preferably 40 to 200 cp is used, and an uneven surface is formed.
[0085]
In the present embodiment, in order to prevent specular reflection, the second interlayer insulating film having the unevenness formed on the surface is formed to form the unevenness on the surface of the pixel electrode. Further, a projection may be formed in a region below the pixel electrode in order to provide light scattering properties by providing unevenness on the surface of the pixel electrode. In that case, the projection can be formed using the same photomask as that for forming the TFT, and thus can be formed without increasing the number of steps. Note that the protrusions may be appropriately provided on the substrate in the pixel portion region other than the wiring and the TFT portion. Thus, irregularities are formed on the surface of the pixel electrode along irregularities formed on the surface of the insulating film covering the convex portions.
[0086]
Alternatively, a film whose surface is planarized may be used as the second interlayer insulating film 462. In that case, after forming the pixel electrode, the surface is made uneven by adding a process such as a known sand blasting method or an etching method to prevent specular reflection and increase the whiteness by scattering the reflected light. Is preferred.
[0087]
Then, in the driver circuit 506, wirings 463 to 467 that are electrically connected to the respective impurity regions are formed. Note that these wirings are formed by patterning a laminated film of a 50-nm-thick Ti film and a 500-nm-thick alloy film (an alloy film of Al and Ti). Of course, the structure is not limited to the two-layer structure, and may be a single-layer structure or a three- or more-layer structure. Further, the material of the wiring is not limited to Al and Ti. For example, a wiring may be formed by forming Al or Cu on a TaN film and then patterning a laminated film on which a Ti film is formed (FIG. 10).
[0088]
In the pixel portion 507, a pixel electrode 470, a gate wiring 469, and a connection electrode 468 are formed. With the connection electrode 468, the source wiring (the lamination of 443a and 443b) is electrically connected to the pixel TFT. The gate wiring 469 is electrically connected to the gate electrode of the pixel TFT. The pixel electrode 470 is electrically connected to the drain region 442 of the pixel TFT, and is also electrically connected to the semiconductor layer 458 which functions as one electrode forming a storage capacitor. In addition, as the pixel electrode 471, it is preferable to use a material having excellent reflectivity, such as a film containing Al or Ag as a main component or a stacked film thereof.
[0089]
As described above, the CMOS circuit including the n-channel TFT 501 and the p-channel TFT 502, the driving circuit 506 including the n-channel TFT 503, and the pixel portion 507 including the pixel TFT 504 and the storage capacitor 505 are formed over the same substrate. can do. Thus, the active matrix substrate is completed.
[0090]
The n-channel TFT 501 of the driver circuit 506 includes a channel formation region 437, a low-concentration impurity region 436 (a GOLD region) overlapping with a first conductive layer 428a which forms part of a gate electrode, and a high-concentration region functioning as a source or drain region. It has an impurity region 452. A p-channel TFT 502 connected to the n-channel TFT 501 with an electrode 466 to form a CMOS circuit includes a channel formation region 440, a high-concentration impurity region 454 functioning as a source region or a drain region, and an impurity element imparting n-type conductivity. And an impurity region 453 into which an impurity element imparting p-type is introduced. In the n-channel TFT 503, a channel formation region 443, a low-concentration impurity region 442 (GOLD region) overlapping with the first conductive layer 430a which forms part of a gate electrode, and a high-concentration impurity functioning as a source region or a drain region. An area 456 is provided.
[0091]
The pixel TFT 504 in the pixel portion includes a channel formation region 446, a low-concentration impurity region 445 (LDD region) formed outside the gate electrode, and a high-concentration impurity region 458 functioning as a source or drain region. Further, an impurity element imparting n-type and an impurity element imparting p-type are added to a semiconductor layer functioning as one electrode of the storage capacitor 505. The storage capacitor 505 is formed using an electrode (a laminate of 432a and 432b) and a semiconductor layer using the insulating film 416 as a dielectric.
[0092]
FIG. 11 is a top view of a pixel portion of an active matrix substrate manufactured in this embodiment. Note that the same reference numerals are used for portions corresponding to FIGS. A chain line A-A 'in FIG. 10 corresponds to a cross-sectional view taken along a chain line A-A' in FIG. Further, a dashed line B-B 'in FIG. 10 corresponds to a cross-sectional view taken along a dashed line B-B' in FIG.
[0093]
The active matrix substrate manufactured as described above has a TFT manufactured using a semiconductor film whose characteristics are close to that of a single crystal, and since the uniformity of the physical properties of the semiconductor film is extremely high, the operating characteristics are high. And reliability can be sufficient. In addition, by combining and optimizing a part of the plurality of linear beams, a uniform laser beam can be formed in the major axis direction, so that the throughput can be improved. Then, by crystallization using the highly uniform laser beam, a highly uniform crystalline semiconductor film can be formed, and variation in electrical characteristics of the TFT can be reduced. Furthermore, in a semiconductor device typified by an active matrix liquid crystal display device using the present invention, it is possible to improve the operating characteristics and reliability of the semiconductor device. In addition, since a solid-state laser can be used instead of using a gas laser as in the conventional laser annealing method, a reduction in the manufacturing cost of a semiconductor device can be realized.
[0094]
[Example 2]
In this embodiment, a process for manufacturing a reflective liquid crystal display device from the active matrix substrate manufactured in Embodiment 1 will be described below. FIG. 12 is used for the description.
[0095]
First, according to the first embodiment, after obtaining the active matrix substrate in the state shown in FIG. 10, an alignment film 567 is formed on at least the pixel electrode 470 on the active matrix substrate shown in FIG. Note that in this embodiment, before forming the alignment film 567, a columnar spacer 572 for maintaining a substrate interval was formed at a desired position by patterning an organic resin film such as an acrylic resin film. Instead of the columnar spacers, spherical spacers may be scattered over the entire surface of the substrate.
[0096]
Next, a counter substrate 569 is prepared. Next, coloring layers 570 and 571 and a planarizing film 573 are formed over the counter substrate 569. The red coloring layer 570 and the blue coloring layer 571 are overlapped to form a light shielding portion. Alternatively, the light-blocking portion may be formed by partially overlapping the red coloring layer and the green coloring layer.
[0097]
In the present embodiment, the substrate shown in Example 1 is used. Therefore, in FIG. 11 showing a top view of the pixel portion of Embodiment 1, at least the gap between the gate wiring 469 and the pixel electrode 470, the gap between the gate wiring 469 and the connection electrode 468, and the gap between the connection electrode 468 and the pixel electrode 470 are reduced. It is necessary to shield light. In this example, the colored layers were arranged such that the light-shielding portion composed of a stack of colored layers overlapped at those positions where light was to be shielded, and the opposing substrates were bonded together.
[0098]
As described above, the number of steps can be reduced by shielding the gap between the pixels with the light-shielding portion formed of the colored layers without forming a light-shielding layer such as a black mask.
[0099]
Next, a counter electrode 576 made of a transparent conductive film was formed at least in the pixel portion over the planarization film 573, an alignment film 574 was formed over the entire surface of the counter substrate, and rubbing treatment was performed.
[0100]
Then, the active matrix substrate on which the pixel portion and the driver circuit are formed and the counter substrate are attached with a sealant 568. A filler is mixed in the sealing material 568, and the two substrates are bonded to each other at a uniform interval by the filler and the columnar spacer. Thereafter, a liquid crystal material 575 is injected between the two substrates, and completely sealed with a sealant (not shown). A known liquid crystal material may be used for the liquid crystal material 575. Thus, the reflection type liquid crystal display device shown in FIG. 12 is completed. Then, if necessary, the active matrix substrate or the opposing substrate is cut into a desired shape. Further, a polarizing plate (not shown) was attached only to the counter substrate. Then, an FPC was attached using a known technique.
[0101]
The liquid crystal display device manufactured as described above has a TFT manufactured using a semiconductor film whose characteristics are close to that of a single crystal, and the uniformity of physical properties of the semiconductor film is extremely high. The operating characteristics and reliability of the device can be sufficient. In addition, by combining and optimizing a part of the plurality of linear beams, a uniform laser beam can be formed in the major axis direction, so that the throughput can be improved. Then, by crystallization using the highly uniform laser beam, a highly uniform crystalline semiconductor film can be formed, and variation in electrical characteristics of the TFT can be reduced. Further, improvement in operation characteristics and reliability of a liquid crystal display device manufactured using the present invention can be realized. Further, since a solid-state laser can be used instead of using a gas laser as in the conventional laser annealing method, a reduction in the manufacturing cost of the liquid crystal display device can be realized. Such a liquid crystal display device can be used as a display unit of various electronic devices.
[0102]
Note that this embodiment can be freely combined with Embodiments 1 and 2.
[0103]
[Example 3]
In this embodiment, an example in which a light-emitting device is manufactured by using the method for manufacturing a TFT for manufacturing an active matrix substrate described in Embodiment 1 will be described. In this specification, a light emitting device is a general term for a display panel in which a light emitting element formed on a substrate is sealed between the substrate and a cover material, and a display module including a TFT in the display panel. is there. Note that the light-emitting element has a layer (light-emitting layer) containing an organic compound capable of obtaining luminescence (Electro Luminescence) generated by applying an electric field, an anode layer, and a cathode layer. The luminescence of the organic compound includes light emission (fluorescence) when returning from the singlet excited state to the ground state and light emission (phosphorescence) when returning from the triplet excited state to the ground state. Alternatively, both light emissions are included.
[0104]
Note that all layers formed between the anode and the cathode in the light emitting element are defined as organic light emitting layers. The organic light emitting layer specifically includes a light emitting layer, a hole injection layer, an electron injection layer, a hole transport layer, an electron transport layer, and the like. Basically, a light-emitting element has a structure in which an anode layer, a light-emitting layer, and a cathode layer are sequentially stacked. In addition to this structure, an anode layer, a hole injection layer, a light-emitting layer, a cathode layer, and an anode layer , A hole injection layer, a light emitting layer, an electron transport layer, a cathode layer, and the like.
[0105]
FIG. 13 is a sectional view of the light emitting device of the present embodiment. 13, a switching TFT 603 provided on a substrate 700 is formed using the n-channel TFT 503 in FIG. Therefore, the description of the structure may refer to the description of the n-channel TFT 503.
[0106]
A driver circuit provided over the substrate 700 is formed using the CMOS circuit in FIG. Therefore, for the description of the structure, the description of the n-channel TFT 501 and the p-channel TFT 502 may be referred to. In this embodiment, a single gate structure is used, but a double gate structure or a triple gate structure may be used.
[0107]
The wirings 701 and 703 function as a source wiring of a CMOS circuit, and the wiring 702 functions as a drain wiring. The wiring 704 functions as a wiring for electrically connecting the source wiring 708 and the source region of the switching TFT, and the wiring 705 functions as a wiring for electrically connecting the drain wiring 709 and the drain region of the switching TFT.
[0108]
Note that the current control TFT 604 is formed using the p-channel TFT 502 in FIG. Therefore, for the description of the structure, the description of the p-channel TFT 502 may be referred to. In this embodiment, a single gate structure is used, but a double gate structure or a triple gate structure may be used.
[0109]
A wiring 706 is a source wiring (corresponding to a current supply line) of the current control TFT, and an electrode 707 is electrically connected to the pixel electrode 711 by being superposed on the pixel electrode 711 of the current control TFT.
[0110]
Note that reference numeral 711 denotes a pixel electrode (anode of the light emitting element) made of a transparent conductive film. As the transparent conductive film, a compound of indium oxide and tin oxide, a compound of indium oxide and zinc oxide, zinc oxide, tin oxide, or indium oxide can be used. Alternatively, a material obtained by adding gallium to a transparent conductive film may be used. The pixel electrode 711 is formed over the flat interlayer insulating film 710 before forming the wiring. In this embodiment, it is very important to flatten the step due to the TFT using the flattening film 710 made of resin. Since a light-emitting layer formed later is extremely thin, poor light emission may be caused by the presence of a step. Therefore, it is desirable to planarize the pixel electrode before forming it so that the light emitting layer can be formed as flat as possible.
[0111]
After forming the wirings 701 to 707, a bank 712 is formed as shown in FIG. The bank 712 may be formed by patterning an insulating film containing 100 to 400 nm of silicon or an organic resin film.
[0112]
Note that since the bank 712 is an insulating film, attention must be paid to electrostatic breakdown of elements during film formation. In this embodiment, the resistivity is reduced by adding carbon particles or metal particles to the insulating film which is the material of the bank 712, and the generation of static electricity is suppressed. At this time, the resistivity is 1 × 10⁶~ 1 × 10¹²Ωm (preferably 1 × 10⁸~ 1 × 10^TenΩm) may be adjusted by adjusting the addition amount of the carbon particles or the metal particles.
[0113]
A light emitting layer 713 is formed over the pixel electrode 711. Although only one pixel is shown in FIG. 13, in this embodiment, light emitting layers corresponding to each color of R (red), G (green), and B (blue) are separately formed. In this embodiment, the low-molecular organic light-emitting material is formed by an evaporation method. Specifically, a 20 nm thick copper phthalocyanine (CuPc) film is provided as a hole injection layer, and a 70 nm thick tris-8-quinolinolato aluminum complex (Alq_Three) It has a laminated structure provided with a film. Alq_ThreeThe emission color can be controlled by adding a fluorescent dye such as quinacridone, perylene, or DCM1 to the dye.
[0114]
However, the above example is an example of an organic light emitting material that can be used as a light emitting layer, and there is no need to limit the present invention to this. A light-emitting layer (a layer for performing light emission and carrier movement therefor) may be formed by freely combining a light-emitting layer, a charge transport layer, or a charge injection layer. For example, in this embodiment, an example in which a low molecular organic light emitting material is used as the light emitting layer has been described, but a medium molecular organic light emitting material or a high molecular organic light emitting material may be used. Note that in this specification, an organic light-emitting material having no sublimability and having a number of molecules of 20 or less or a chain of molecules having a length of 10 μm or less is defined as a medium-molecular-weight organic light-emitting material. As an example of using a high molecular weight organic light emitting material, a 20 nm polythiophene (PEDOT) film is provided as a hole injection layer by spin coating, and a 100 nm paraphenylene vinylene (PPV) film is provided thereon as a light emitting layer. A stacked structure may be used. When a π-conjugated polymer of PPV is used, the emission wavelength can be selected from red to blue. Further, an inorganic material such as silicon carbide can be used for the charge transport layer and the charge injection layer. Known materials can be used for these organic light emitting materials and inorganic materials.
[0115]
Next, a cathode 714 made of a conductive film is provided over the light-emitting layer 713. In this embodiment, an alloy film of aluminum and lithium is used as the conductive film. Of course, a known MgAg film (an alloy film of magnesium and silver) may be used. As the cathode material, a conductive film made of an element belonging to Group 1 or 2 of the periodic table or a conductive film to which those elements are added may be used.
[0116]
The light emitting element 715 is completed at the time when the cathode 714 is formed. Note that the light-emitting element 715 here refers to a diode formed by the pixel electrode (anode) 711, the light-emitting layer 713, and the cathode 714.
[0117]
It is effective to provide the passivation film 716 so as to completely cover the light emitting element 715. As the passivation film 716, an insulating film including a carbon film, a silicon nitride film, or a silicon nitride oxide film is used, and the insulating film is used as a single layer or as a stacked layer.
[0118]
At this time, it is preferable to use a film having good coverage as the passivation film, and it is effective to use a carbon film, particularly a DLC film. Since the DLC film can be formed in a temperature range from room temperature to 100 ° C. or less, it can be easily formed above the light-emitting layer 713 having low heat resistance. In addition, the DLC film has a high blocking effect against oxygen, and can suppress oxidation of the light-emitting layer 713. Therefore, the problem that the light emitting layer 713 is oxidized during the subsequent sealing step can be prevented.
[0119]
Further, a sealing material 717 is provided over the passivation film 716, and a cover material 718 is attached. As the sealing material 717, an ultraviolet curable resin may be used, and it is effective to provide a substance having a moisture absorbing effect or a substance having an antioxidant effect inside. In this embodiment, as the cover material 718, a glass substrate, a quartz substrate, a plastic substrate (including a plastic film), or a flexible substrate on which carbon films (preferably DLC films) are formed on both surfaces is used. Other than the carbon film, an aluminum film (AlON, AlN, AlO, etc.), SiN, or the like can be used.
[0120]
Thus, a light emitting device having a structure as shown in FIG. 13 is completed. Note that it is effective to continuously process the steps from the formation of the bank 712 to the formation of the passivation film 716 without exposing to the atmosphere using a multi-chamber (or in-line) film forming apparatus. . Further, by further developing, it is also possible to continuously process up to the step of bonding the cover material 718 without releasing it to the atmosphere.
[0121]
Thus, the n-channel TFTs 601 and 602, the switching TFT (n-channel TFT) 603, and the current control TFT (n-channel TFT) 604 are formed on the substrate 700.
[0122]
Further, as described with reference to FIGS. 13A and 13B, an n-channel TFT which is resistant to deterioration due to a hot carrier effect can be formed by providing an impurity region overlapping a gate electrode with an insulating film interposed therebetween. Therefore, a highly reliable light-emitting device can be realized.
[0123]
In this embodiment, only the configuration of the pixel portion and the driving circuit is shown. However, according to the manufacturing process of this embodiment, other logic circuits such as a signal division circuit, a D / A converter, an operational amplifier, and a γ correction circuit are also provided. Can be formed on the same insulator, and further, a memory or a microprocessor can be formed.
[0124]
The light-emitting device manufactured as described above has a TFT manufactured using a semiconductor film whose characteristics are close to that of a single crystal, and the uniformity of physical properties of the semiconductor film is extremely high. Operational characteristics and reliability may be sufficient. In addition, by combining and optimizing a part of the plurality of linear beams, a uniform laser beam can be formed in the major axis direction, so that the throughput can be improved. Then, by crystallization using the highly uniform laser beam, a highly uniform crystalline semiconductor film can be formed, and variation in electrical characteristics of the TFT can be reduced. Further, it is possible to realize an improvement in operation characteristics and reliability of a light emitting device manufactured using the present invention. Further, since a solid-state laser can be used instead of using a gas laser as in the conventional laser annealing method, the manufacturing cost of the light emitting device can be reduced. Such a light emitting device can be used as a display unit of various electronic devices.
[0125]
Note that this embodiment can be freely combined with Embodiments 1 and 2.
[0126]
[Example 4]
By applying the present invention, various semiconductor devices (an active matrix liquid crystal display device, an active matrix light emitting device, and an active matrix EC display device) can be manufactured. That is, the present invention can be applied to various electronic apparatuses in which the electro-optical devices are incorporated in a display unit.
[0127]
Such electronic devices include video cameras, digital cameras, projectors, head mounted displays (goggle-type displays), car navigation systems, car stereos, personal computers, personal digital assistants (mobile computers, mobile phones, e-books, etc.). No. Examples of these are shown in FIGS. 14, 15 and 16.
[0128]
FIG. 14A illustrates a personal computer, which includes a main body 3001, an image input unit 3002, a display unit 3003, a keyboard 3004, and the like. The personal computer of the present invention is completed by applying the semiconductor device manufactured according to the present invention to the display portion 3003.
[0129]
FIG. 14B illustrates a video camera, which includes a main body 3101, a display portion 3102, an audio input portion 3103, operation switches 3104, a battery 3105, an image receiving portion 3106, and the like. The video camera of the present invention is completed by applying the semiconductor device manufactured according to the present invention to the display portion 3102.
[0130]
FIG. 14C illustrates a mobile computer (mobile computer), which includes a main body 3201, a camera section 3202, an image receiving section 3203, operation switches 3204, a display section 3205, and the like. The mobile computer of the present invention is completed by applying the semiconductor device manufactured according to the present invention to the display portion 3205.
[0131]
FIG. 14D illustrates a goggle-type display, which includes a main body 3301, a display portion 3302, an arm portion 3303, and the like. The display portion 3302 uses a flexible substrate as a substrate, and the display portion 3302 is curved to manufacture a goggle-type display. It also realizes a lightweight and thin goggle type display. The goggle type display of the present invention is completed by applying the semiconductor device manufactured according to the present invention to the display portion 3302.
[0132]
FIG. 14E illustrates a player using a recording medium on which a program is recorded (hereinafter, referred to as a recording medium), which includes a main body 3401, a display portion 3402, a speaker portion 3403, a recording medium 3404, operation switches 3405, and the like. This player uses a DVD (Digital Versatile Disc), a CD, or the like as a recording medium, and can enjoy music, movies, games, and the Internet. The recording medium of the present invention is completed by applying the semiconductor device manufactured according to the present invention to the display portion 3402.
[0133]
FIG. 14F illustrates a digital camera, which includes a main body 3501, a display portion 3502, an eyepiece portion 3503, operation switches 3504, an image receiving portion (not shown), and the like. The digital camera of the present invention is completed by applying the semiconductor device manufactured according to the present invention to the display portion 3502.
[0134]
FIG. 15A illustrates a front type projector, which includes a projection device 3601, a screen 3602, and the like. The front type projector of the present invention is completed by applying the semiconductor device manufactured according to the present invention to the liquid crystal display device 3808 and other driving circuits which constitute a part of the projection device 3601.
[0135]
FIG. 15B illustrates a rear projector, which includes a main body 3701, a projection device 3702, a mirror 3703, a screen 3704, and the like. The rear-type projector of the present invention is completed by applying the semiconductor device manufactured according to the present invention to the liquid crystal display device 3808 and another driving circuit which constitute a part of the projection device 3702.
[0136]
Note that FIG. 15C is a diagram illustrating an example of the structure of the projection devices 3601 and 3702 in FIGS. 15A and 15B. Each of the projection devices 3601 and 3702 includes a light source optical system 3801, mirrors 3802 and 3804 to 3806, a dichroic mirror 3803, a prism 3807, a liquid crystal display device 3808, a phase difference plate 3809, and a projection optical system 3810. The projection optical system 3810 is configured by an optical system including a projection lens. In this embodiment, an example of a three-plate type is shown, but there is no particular limitation, and for example, a single-plate type may be used. Further, the practitioner may appropriately provide an optical system such as an optical lens, a film having a polarizing function, a film for adjusting a phase difference, and an IR film in an optical path indicated by an arrow in FIG. Good.
[0137]
FIG. 15D illustrates an example of the structure of the light source optical system 3801 in FIG. In this embodiment, the light source optical system 3801 includes a reflector 3811, a light source 3812, lens arrays 3813 and 3814, a polarization conversion element 3815, and a condenser lens 3816. Note that the light source optical system shown in FIG. 15D is an example and is not particularly limited. For example, a practitioner may appropriately provide an optical system such as an optical lens, a film having a polarizing function, a film for adjusting a phase difference, and an IR film in the light source optical system.
[0138]
However, in the projector shown in FIG. 15, a case in which a transmissive electro-optical device is used is shown, and an application example in a reflective electro-optical device and a light emitting device is not shown.
[0139]
FIG. 16A illustrates a mobile phone, which includes a main body 3901, an audio output portion 3902, an audio input portion 3903, a display portion 3904, operation switches 3905, an antenna 3906, and the like. The mobile phone of the present invention is completed by applying the semiconductor device manufactured according to the present invention to the display portion 3904.
[0140]
FIG. 16B illustrates a portable book (e-book) including a main body 4001, display portions 4002 and 4003, a storage medium 4004, operation switches 4005, an antenna 4006, and the like. The portable book of the present invention is completed by applying the semiconductor device manufactured according to the present invention to the display portions 4002 and 4003. Mobile books can be as large as paperback books, making them easy to carry.
[0141]
FIG. 16C illustrates a display, which includes a main body 4101, a support 4102, a display portion 4103, and the like. The display portion 4103 is manufactured using a flexible substrate, so that a lightweight and thin display can be realized. Further, the display portion 4103 can be curved. The display of the present invention is completed by applying the semiconductor device manufactured by the present invention to the display portion 4103. The display of the present invention is particularly advantageous when the screen is enlarged, and is advantageous for a display having a diagonal size of 10 inches or more (especially 30 inches or more).
[0142]
The electronic device manufactured as described above has a TFT manufactured using a semiconductor film whose characteristics are close to that of a single crystal, and the uniformity of physical properties of the semiconductor film is extremely high. Operational characteristics and reliability may be sufficient. In addition, by combining and optimizing a part of the plurality of linear beams, a uniform laser beam can be formed in the major axis direction, so that the throughput can be improved. Then, by crystallization using the highly uniform laser beam, a highly uniform crystalline semiconductor film can be formed, and variation in electrical characteristics of the TFT can be reduced. Furthermore, in a semiconductor device typified by an active matrix liquid crystal display device using the present invention, it is possible to improve the operating characteristics and reliability of the semiconductor device. In addition, since a solid-state laser can be used instead of using a gas laser as in the conventional laser annealing method, a reduction in the manufacturing cost of a semiconductor device can be realized.
[0143]
Further, the applicable range of the present invention is extremely wide, and the present invention can be applied to electronic devices in various fields. Note that the electronic apparatus of the present embodiment can also be realized by using a configuration composed of a combination of Embodiments 1 and 2 and Embodiments 1, 2, or 1, 3.
[0144]
【The invention's effect】
By adopting the configuration of the present invention, the following basic significance can be obtained.
(A) Irradiation of a plurality of laser beams that satisfies the formula shown in the present invention onto the irradiation target enables more uniform laser annealing.
(B) The object to be irradiated can be uniformly annealed. In particular, it is suitable for crystallization of a semiconductor film, improvement of crystallinity, and activation of an impurity element.
(C) Since a part of the plurality of linear beams is combined with each other, it is possible to improve the throughput.
(D) Since a solid-state laser can be used instead of using a gas laser unlike the conventional laser annealing method, a reduction in the manufacturing cost of a semiconductor device can be realized.
(E) In addition to satisfying the above advantages, in a semiconductor device typified by an active matrix liquid crystal display device, it is possible to improve the operation characteristics and reliability of the semiconductor device. Further, reduction in manufacturing cost of the semiconductor device can be realized.
[Brief description of the drawings]
FIG. 1 illustrates Embodiment 1;
FIG. 2 illustrates Embodiment 1;
FIG. 3 illustrates Embodiment 1;
FIG. 4 illustrates Embodiment 1;
FIG. 5 illustrates Embodiment 2;
FIG. 6 illustrates Embodiment 1;
FIG. 7 illustrates Embodiment 1;
FIG. 8 is a cross-sectional view illustrating a manufacturing process of a pixel TFT and a TFT of a driver circuit.
FIG. 9 is a cross-sectional view illustrating a manufacturing process of a pixel TFT and a TFT of a driver circuit.
FIG. 10 is a cross-sectional view illustrating a manufacturing process of a pixel TFT and a TFT of a driver circuit.
FIG. 11 is a top view illustrating a configuration of a pixel TFT.
FIG. 12 is a cross-sectional view illustrating a manufacturing process of an active matrix liquid crystal display device.
FIG. 13 is a cross-sectional structure diagram of a driving circuit and a pixel portion of a light-emitting device.
FIG. 14 illustrates an example of a semiconductor device.
FIG. 15 illustrates an example of a semiconductor device.
FIG. 16 illustrates an example of a semiconductor device.

Claims (18)

In the case where the shapes of the plurality of laser beams emitted from the plurality of laser oscillators are round, the plurality of laser beams are stretched to extend the major axis e- ² width a and the minor axis e- ² width b. When processing into a shaped beam and overlapping the ends in the major diameter direction to form a longer linear beam, the center coordinates of the mutually overlapping laser beams among the plurality of laser beams are (x, y), ( x ′, y ′), the coordinates are set in parallel with the major axis and the x axis, and the coordinates are set in parallel with the minor axis and the y axis.
((X-x ') / a) 2 + ((y-y') / b) 2 <0.72 2
Or
((X-x ') / a) 2 + ((y-y') / b) 2 <0.63 2
A laser irradiation method characterized by satisfying the following. In the case where the shapes of the plurality of laser beams emitted from the plurality of laser oscillators are rectangular, the plurality of laser beams are stretched to extend the major axis e- ² width a and the minor axis e- ² width b. When processing into a shaped beam and overlapping the ends in the major diameter direction to form a longer linear beam, the center coordinates of the mutually overlapping laser beams among the plurality of laser beams are (x, y), ( x ′, y ′), the coordinates are set in parallel with the major axis and the x axis, and the coordinates are set in parallel with the minor axis and the y axis.
| Y−y ′ | / b <0.72 and | xx ′ | <a
Or
| Y−y ′ | / b <0.63 and | xx ′ | <a
Wherein the energy distribution in the major axis direction of the linear beam is uniform, and the energy distribution in the minor axis direction is Gaussian. In the case where the shapes of the plurality of laser beams emitted from the plurality of laser oscillators are rectangular, the plurality of laser beams are stretched to extend the major axis e- ² width a and the minor axis e- ² width b. When processing into a shaped beam and overlapping the ends in the major diameter direction to form a longer linear beam, the center coordinates of the mutually overlapping laser beams among the plurality of laser beams are (x, y), ( x ′, y ′), the coordinates are set in parallel with the major axis and the x axis, and the coordinates are set in parallel with the minor axis and the y axis.
| Xx ′ | / a <0.72 and | yy ′ | <b
Or
| Xx ′ | / a <0.63, and | y−y ′ | <b, the energy distribution in the minor axis direction of the linear beam is uniform, and the energy distribution in the major axis direction is Gaussian. A laser irradiation method characterized by the above-mentioned. In the case where the shapes of the plurality of laser beams emitted from the plurality of laser oscillators are rectangular, the plurality of laser beams are stretched to extend the major axis e- ² width a and the minor axis e- ² width b. When processing into a shaped beam and overlapping the ends in the major diameter direction to form a longer linear beam, the center coordinates of the mutually overlapping laser beams among the plurality of laser beams are (x, y), ( x ′, y ′), the coordinates are set in parallel with the major axis and the x axis, and the coordinates are set in parallel with the minor axis and the y axis.
| Xx ′ | / a <0.72, and | yy ′ | / b <0.72
Or
| Xx ′ | / a <0.63, and | yy ′ | / b <0.63
Wherein the energy distribution in the minor axis direction of the linear beam is Gaussian and the energy distribution in the major axis direction is Gaussian. In the case where the shapes of the plurality of laser beams emitted from the plurality of laser oscillators are round and rectangular, the plurality of laser beams are stretched to have a longer e- ² width of a and a shorter e- ² width of e. When processing into a linear beam of b and overlapping the ends in the major diameter direction to form a longer linear beam, the center coordinates of the mutually overlapping laser beams of the plurality of laser beams are respectively (x, y ), (X ′, y ′), the coordinates are set in parallel with the major axis and the x axis, and the coordinates are set in parallel with the minor axis and the y axis.
((Xx ′) / a) ² + ((y−y ′) / b) ² <(0.72) ²
Or
((Xx ′) / a) ² + ((yy ′) / b) ² <(0.63) ²
A laser irradiation method characterized by satisfying the following. 6. The method according to claim 1, wherein the e- ² width a of the major axis and the center coordinates (x, y) and (x ', y') of the adjacent laser beams are | xx '|. /a>0.52
A laser irradiation method characterized by satisfying the following. 7. The laser irradiation method according to claim 1, wherein the laser is selected from a continuous wave gas laser, a solid laser, and a metal laser. 8. The laser irradiation method according to claim 1, wherein an e− ² width b of the minor axis is 50 μm or less. 9. The laser according to claim 1, wherein the laser includes an Ar laser, a Kr laser, a CO ₂ laser, a YAG laser, a YVO ₄ laser, a YLF laser, a YAlO ₃ laser, a Y ₂ O ₃ laser, a glass laser, A laser irradiation method characterized by being selected from ruby laser, alexandrite laser, Ti: sapphire laser, helium cadmium laser, copper vapor laser and gold vapor laser. In the case where the shape of the plurality of laser beams emitted from a plurality of laser oscillators are round-shaped, a plurality of laser beams at the semiconductor film on or near the major axis e ^-2 width a, the minor axis e ^{- (2)} Processing into a linear beam having a width of b, overlapping the ends in the major axis direction of each other, and forming a longer linear beam, the center coordinates of the laser beams overlapping each other among the plurality of laser beams, respectively. When (x, y) and (x ', y') are set, the coordinates are set in parallel with the major axis and the x-axis, and the coordinates are set in parallel with the minor axis and the y-axis.
((Xx ′) / a) ² + ((y−y ′) / b) ² <(0.72) ²
Or
((Xx ′) / a) ² + ((yy ′) / b) ² <(0.63) ²
And a method for manufacturing a semiconductor device. In the case where the shape of the plurality of laser beams emitted from a plurality of laser oscillators are rectangular, the plurality of laser beams at the semiconductor film on or near the major axis e ^-2 width a, the minor axis e ^{- (2) When} processing into a linear beam having a width b and overlapping the ends in the major axis direction with each other to form a longer linear beam, the center coordinates of the mutually overlapping laser beams among the plurality of laser beams are respectively ( x, y) and (x ', y'), the coordinates are set in parallel with the major axis and the x axis, and the coordinates are set in parallel with the minor axis and the y axis.
| Y−y ′ | / b <0.72 and | xx ′ | <a
Or
| Yy ′ | / b <0.63 and | xx ′ | <a
Wherein the energy distribution in the major axis direction of the linear beam is uniform and the energy distribution in the minor axis direction is Gaussian. In the case where the shape of the plurality of laser beams emitted from a plurality of laser oscillators are rectangular, the plurality of laser beams at the semiconductor film on or near the major axis e ^-2 width a, the minor axis e ^{- (2) When} processing into a linear beam having a width b and overlapping the ends in the major axis direction with each other to form a longer linear beam, the center coordinates of the mutually overlapping laser beams among the plurality of laser beams are respectively ( x, y) and (x ', y'), the coordinates are set in parallel with the major axis and the x axis, and the coordinates are set in parallel with the minor axis and the y axis.
| Xx ′ | / a <0.72 and | yy ′ | <b
Or
| Xx ′ | / a <0.63, and | yy ′ | <b
Wherein the energy distribution in the minor axis direction of the linear beam is uniform and the energy distribution in the major axis direction is Gaussian. In the case where the shape of the plurality of laser beams emitted from a plurality of laser oscillators are rectangular, the plurality of laser beams at the semiconductor film on or near the major axis e ^-2 width a, the minor axis e ^{- (2)} processing into a linear beam having a width b, overlapping the ends in the major axis direction with each other, and forming a longer linear beam, when forming a longer linear beam, the center coordinates of the mutually overlapping laser beams among the plurality of laser beams When (x, y) and (x ', y') are set, the coordinates are set in parallel with the major axis and the x axis, and the coordinates are set in parallel with the minor axis and the y axis.
| Xx ′ | / a <0.72, and | yy ′ | / b <0.72
Or
| Xx ′ | / a <0.63, and | yy ′ | / b <0.63
Wherein the energy distribution in the major axis direction of the linear beam is Gaussian and the energy distribution in the minor axis direction is Gaussian. In the case where the shapes of the plurality of laser beams emitted from the plurality of laser oscillators are round and rectangular, the plurality of laser beams are formed on the semiconductor film or in the vicinity of the semiconductor film at a major axis where e- ² width is a and minor axis is a. The e- ² width is processed into a linear beam having a width b, and the ends in the major diameter direction are overlapped with each other to form a longer linear beam. When forming a longer linear beam, the center coordinates of the laser beams overlapping each other among the plurality of laser beams When (x, y) and (x ′, y ′) are respectively set, the coordinates are set in parallel with the major axis and the x axis, and the coordinates are set in parallel with the minor axis and the y axis.
((Xx ′) / a) ² + ((y−y ′) / b) ² <(0.72) ²
Or
((Xx ′) / a) ² + ((yy ′) / b) ² <(0.63) ²
And a method for manufacturing a semiconductor device. 15. The apparatus according to claim 10, wherein the e- ² width a of the major axis and the center coordinates (x, y) and (x ′, y ′) of the adjacent laser beams are | xx ′ |. /a>0.52
And a method for manufacturing a semiconductor device. The method for manufacturing a semiconductor device according to any one of claims 10 to 15, wherein the laser oscillator is selected from a continuous wave gas laser, a solid-state laser, and a metal laser. 17. The method for manufacturing a semiconductor device according to claim 10, wherein the width e- ^{2 of the} minor axis is 50 μm or less. According to any one of claims 10 to 17, wherein the laser oscillator, Ar laser, Kr laser, CO ₂ laser, YAG laser, YVO ₄ laser, YLF laser, YAlO ₃ laser, Y ₂ O ₃ laser, a glass laser, A method for manufacturing a semiconductor device, which is selected from a ruby laser, an alexandrite laser, a Ti: sapphire laser, a helium cadmium laser, a copper vapor laser, and a gold vapor laser.

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