JP2000315652A - Method for crystalizing semiconductor thin film and laser irradiation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To uniformize crystallinity in an overlapped part and a non-overalpped part, when irradiation areas of laser light are overlapped and a semiconductor thin film having a large area is crystalized. SOLUTION: In this crystalization method, the surface of a substrate 1 is divided along a dividing line DL into a first divided area D1 and a second divided area D2, while a laser light is shaped and an irradiation region R is adjusted so that the respective divided regions D1 and D2 are partly irradiated. The first divided region D1 is repeatedly irradiated by a laser light, while the irradiation region R is scanned parallel to the dividing line DL, and a semiconductor thin film 2 included in the first divided region D1 is crystallized. Likewise, a semiconductor thin film 2 included in the second divided region D2 is crystallized. In this case, the irradiation region R of the laser light emitted to the first divided area D1 and that emitted to the second divided region D2 are overlapped each other on their end parts. An overlapped part W is adjusted in a manner that its width WX parallel to the dividing DL may be 80% or less of a width VX of a non-overlapped part V. In addition, an intensity EW of laser light energy in the overlapped part is controlled to 95% or less of energy concentration EV in the non-overlapped part V.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for crystallizing a semiconductor thin film and a laser irradiation apparatus used for the method.
Further, the present invention relates to a thin film transistor and a display device manufactured by using these methods and apparatuses.

[0002]

2. Description of the Related Art Crystallization annealing using laser light has been developed as a part of a method for lowering the temperature of a manufacturing process of a thin film transistor. This is done by irradiating laser light to a non-single-crystal semiconductor thin film such as amorphous silicon or relatively small-diameter polycrystalline silicon formed on an insulating substrate, heating the film locally, and then cooling it. This converts (crystallizes) the semiconductor thin film into polycrystal having a relatively large particle size. Using the crystallized semiconductor thin film as an active layer (channel region), a thin film transistor is integrated and formed. By adopting such crystallization annealing, a low-temperature process of a thin film semiconductor device can be performed, and an inexpensive glass substrate can be used instead of an expensive quartz substrate having excellent heat resistance.

In crystallization annealing, generally, pulsed laser irradiation is performed intermittently while partially overlapping a line of laser light along the scanning direction. By overlapping the laser beams, crystallization of the semiconductor thin film can be performed relatively uniformly. FIG. 14 schematically shows crystallization annealing using a linear laser beam (line beam). A laser beam 50 shaped into a line along the Y direction of the insulating substrate 1 made of glass or the like is irradiated from the surface side of the insulating substrate 1 on which a semiconductor thin film has been formed in advance. At this time, the insulating substrate 1 is moved in the X direction relative to the irradiation area. Here, the line beam 50 emitted from the excimer laser light source is emitted intermittently and partially overlapping. That is, the insulating substrate 0 is scanned relative to the line beam 50 in the X direction via the stage. The stage is moved for each one shot at a pitch smaller than the width dimension of the line beam 50, and crystallization annealing is performed so that the line beam 50 can be applied to the entire substrate 1.

[0004]

The length of the long axis (Y direction) of the line beam (long beam) used for the above-mentioned crystallization annealing depends on the design of an optical system for shaping the beam and the adjustment of the optical system. 200-300m due to difficulty
m is the limit. Therefore, the region that can be annealed in one scanning step (one irradiation step) is determined by the length of the long axis of the long beam. In the long axis direction (Y
Direction). However, when such superposition is performed, the intensity of the laser beam at the superposed portion becomes too strong and the crystallinity is deteriorated, so that a thin film transistor having a performance usable for a display device cannot be produced. Therefore, at present, when a line beam having a major axis dimension of 200 mm is used, a flat panel display device having a diagonal dimension of 12.1 inches or more cannot be produced.

In order to obtain a good display device, it is important to form a good thin film transistor over the entire surface of the substrate. For that purpose, it is necessary to form a polycrystalline semiconductor thin film having a large grain size and uniform crystallinity over the entire surface of the substrate. However, at present, as described above, when a large area substrate is subjected to crystallization annealing, when a line beam is overlapped and irradiated in the long axis direction, the crystallinity of the overlapped portion is deteriorated, and the performance of the thin film transistor is deteriorated. cause. If the display device is created in this state, the overlapped portion appears as an image defect.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art, and when performing crystallization annealing by irradiating a semiconductor thin film with a laser beam, a laser beam irradiation region is formed. An object of the present invention is to provide a method and an apparatus for obtaining a uniform and large-diameter semiconductor thin film over the entire surface of a substrate without deteriorating the crystallinity of an overlapped portion. The following measures were taken to achieve this purpose. That is, in order to perform crystallization by irradiating a semiconductor thin film previously formed on a substrate with a laser beam, the surface of the substrate is divided into regions to define at least first and second divided regions, while shaping the laser beam. A preparation step of adjusting a laser light irradiation area so that at least each of the divided areas can be partially irradiated, and irradiating the first divided area with laser light at least once to the first divided area. A first irradiation step of crystallizing the semiconductor thin film included therein, and a second irradiation step of irradiating the second divided region with laser light at least once to crystallize the semiconductor thin film included in the second divided region In the method of crystallizing a semiconductor thin film including the above, the irradiation region of the laser beam irradiated to the first divided region and the irradiation region of the laser light irradiated to the second divided region overlap each other at an end, and Fewer edges with overlapping in the area Both the energy density of the laser beam at one side, compared with the energy density of the laser beam portions causing no overlapping 9
It is characterized by being controlled to 5% or less. Preferably, the preparing step adjusts the irradiation area of the laser beam into a long shape along a predetermined long axis, and the first irradiation step is performed along a short axis orthogonal to the long axis with respect to the first divided area. Repeatedly irradiating laser light while scanning the irradiation area, the second irradiation step repeatedly irradiates laser light while scanning the irradiation area along the short axis to the second divided area, The irradiation region of the laser beam irradiated on the divided region and the irradiation region of the laser beam irradiated on the second divided region are overlapped at the long-axis end portion of the elongated shape.

Further, in order to perform crystallization by irradiating a semiconductor thin film previously formed on the substrate with a laser beam, the surface of the substrate is partitioned along a dividing line to define at least first and second divided regions. On the other hand, a preparatory step of adjusting the laser light irradiation area so that at least each of the divided areas can be partially irradiated by shaping the laser light, and setting the irradiation area to the first divided area in a direction parallel to the division line A first irradiation step of repeatedly irradiating laser light while scanning to crystallize a semiconductor thin film included in the first divided region, and a direction in which the irradiated region is parallel to the divided line with respect to the second divided region. A second irradiation step of irradiating a laser beam repeatedly while scanning to crystallize the semiconductor thin film included in the second divided region, wherein the first divided region is irradiated with the first divided region. Laser light irradiation area and second The irradiation regions of the laser light applied to the split region overlap each other at the ends, and at least one of the ends where the overlap occurs in the irradiation region has a width dimension parallel to the dividing line, which is a portion where the overlap does not occur. 80 compared to width
% Or less. Preferably, the preparation step adjusts the irradiation area of the laser beam into a long shape along a direction orthogonal to the division line, and the first irradiation step is performed in parallel with the division line with respect to the first division area. The laser beam is repeatedly irradiated while scanning the irradiation area along the direction, and the second irradiation step is to scan the irradiation area along the direction parallel to the division line for the second division area. Are repeatedly irradiated, and the irradiation region of the laser beam irradiated to the first divided region and the irradiation region of the laser beam irradiated to the second divided region are overlapped at the end of the elongated shape.

In order to crystallize the semiconductor thin film by irradiating the semiconductor thin film formed on the substrate in advance with a laser beam, at least first and second divided regions are defined by dividing the surface of the substrate into regions. Means for adjusting the laser light irradiation area so that the laser light can be shaped and at least partially irradiate each of the divided areas, and irradiating the laser light once or more to the first divided area. Means for crystallizing the semiconductor thin film included in the first divided region, and further irradiating the second divided region with laser light at least once to crystallize the semiconductor thin film included in the second divided region. In the provided laser irradiation device, the irradiation region of the laser light irradiated to the first divided region and the irradiation region of the laser light irradiated to the second divided region overlap each other at the end, and within the irradiation region At least one side of the overlapping end The energy density of the definitive laser beam, characterized in that it comprises means for controlling 95% or less compared with the energy density of the laser beam portions causing no overlapping.

Further, in order to perform crystallization by irradiating a semiconductor thin film previously formed on a substrate with a laser beam, the surface of the substrate is divided along a dividing line to define at least first and second divided regions. Means for adjusting the irradiation area of the laser beam so that at least each of the divided areas can be partially irradiated by shaping the laser light, and setting the irradiation area with respect to the first divided area in a direction parallel to the division line. The semiconductor thin film included in the first divided region is crystallized by repeatedly irradiating a laser beam while scanning, and the irradiation region is repeatedly scanned with respect to the second divided region in a direction parallel to the dividing line. Means for irradiating a laser beam and crystallizing a semiconductor thin film included in the second divided region, wherein the irradiation region of the laser beam irradiated to the first divided region and the second Irradiation of laser light applied to the divided area The regions overlap each other at the ends, and at least one of the ends where the overlap occurs in the irradiation region is such that the width dimension parallel to the dividing line is 80% or less of the width dimension of the non-overlapping part. It is characterized by having a means for adjusting the distance.

A thin film transistor having a laminated structure including a semiconductor thin film, a gate insulating film overlaid on one surface thereof, and a gate electrode overlaid on the semiconductor thin film via the gate insulating film, wherein the semiconductor thin film is After forming amorphous silicon or polycrystalline silicon having a relatively small particle size on a substrate, the substrate is irradiated with a laser beam and crystallized into polycrystalline silicon having a relatively large particle size. After dividing the area and defining at least the first and second divided areas, after adjusting the irradiation area of the laser light so that the laser light can be shaped and at least each of the divided areas can be partially irradiated,
The semiconductor thin film included in the first divided region is irradiated with laser light at least once on the first divided region to crystallize, and further irradiated with the laser light at least once on the second divided region. The semiconductor thin film included in the second divided region is crystallized, and the irradiation region of the laser light irradiated to the first divided region and the irradiation region of the laser light irradiated to the second divided region are mutually separated. After overlapping at the end, the crystal is controlled by controlling the energy density of the laser beam on at least one side of the end where the overlap occurs in the irradiation area to 95% or less of the energy density of the laser light on the part where the overlap does not occur. It is characterized by the fact that

A thin film transistor having a laminated structure including a semiconductor thin film, a gate insulating film overlaid on one surface thereof, and a gate electrode overlaid on the semiconductor thin film via the gate insulating film, wherein the semiconductor thin film is After forming amorphous silicon or polycrystalline silicon having a relatively small particle size on a substrate, the substrate is irradiated with a laser beam and crystallized into polycrystalline silicon having a relatively large particle size. While defining along the dividing line and defining at least the first and second divided areas, after adjusting the irradiation area of the laser light so as to be able to partially irradiate at least each divided area by shaping the laser light, A laser beam is repeatedly irradiated on the first divided region while scanning the irradiation region in a direction parallel to the division line to crystallize a semiconductor thin film included in the first divided region, and further a second divided region is formed. On the other hand, the semiconductor thin film included in the second divided region is crystallized by repeatedly irradiating laser light while scanning the irradiated region in a direction parallel to the division line, and is irradiated to the first division region. After the irradiation region of the laser beam and the irradiation region of the laser beam irradiated to the second divided region overlap each other at the ends, at least one of the ends where the overlapping occurs in the irradiation region is at least one of the division line. It is characterized in that it is crystallized by adjusting the parallel width dimension to be 80% or less of the width dimension of the portion where no overlap occurs.

According to the present invention, when a thin film transistor using a polycrystalline semiconductor thin film as an active layer is basically produced, an amorphous layer obtained by a low pressure chemical vapor deposition method (LPCVD method), a plasma CVD method, a sputtering method, or the like. A high quality semiconductor thin film or a polycrystalline semiconductor thin film having a relatively small grain size is converted into a polycrystalline semiconductor thin film having a relatively large grain size by irradiating a laser beam. When irradiating an amorphous semiconductor thin film or the like with an excimer laser beam for crystallization, for example, a long beam is used to scan the irradiation region in the short axis direction. When performing uniform crystallization annealing on a substrate having a large area not less than the major axis, the substrate is divided into regions, and a long beam scanning step is performed for each divided region. At this time, an overlapping portion is formed at the long-axis end of the long beam along the division line of the adjacent divided regions. In the present invention, the width of the long beam in the short axis direction at the overlapped portion is set to 80% or less of the width at the non-overlapping portion. Alternatively, the energy density of the overlapping portion is adjusted to be 95% or less of the energy density of the non-overlapping portion. In some cases, the laser beam may be shaped so as to satisfy the above two conditions simultaneously. When adjusting the energy density of the superimposed portion, the present invention is not limited to the repetitive irradiation method in which scanning is performed while overlapping the irradiation regions, but may be applied to a method in which each divided region is irradiated collectively. In the above description, a long laser beam is used. However, the present invention is not limited to this, and can be applied to a rectangular laser beam. As described above, by relatively adjusting the laser light intensity of the superposed portion and the laser light intensity of the non-superposed portion, a uniform polycrystalline semiconductor thin film can be formed over the entire surface of the substrate, and a high-performance thin film transistor A polycrystalline semiconductor thin film having a uniform particle size, which can be sufficiently used as an active layer, can be formed over the entire surface of a large-area substrate.

[0013]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a schematic diagram illustrating an example of a method for crystallizing a semiconductor thin film according to the present invention. In order to crystallize the semiconductor thin film 2 previously formed on the substrate 1 by irradiating the semiconductor thin film 2 with a laser beam, a preparation process according to the size of the substrate is performed. Specifically, as shown in (a), the surface of the substrate 1 is sectioned along the division line DL to define at least a first division region D1 and a second division region D2. If the size of the substrate 1 is even larger, the third divided area, the fourth divided area,...
Is provided. On the other hand, the laser light irradiation region R is adjusted so that the laser light is shaped and at least each of the divided regions D can be partially irradiated. Here, the first irradiation step is performed, and the first divided region D1 is repeatedly irradiated with laser light while scanning the irradiation region R in a direction parallel to the division line DL, so that the semiconductor thin film included in the first divided region D1 is irradiated. 2 is crystallized. The portion of the semiconductor thin film 2 crystallized in the first irradiation step is schematically shown in FIG. Subsequently, a second irradiation step is performed. The semiconductor thin film 2 included in the second divided region D2 is repeatedly irradiated with laser light while scanning the irradiated region R in a direction parallel to the division line DL with respect to the second divided region D2. Is crystallized. The portion of the semiconductor thin film 2 crystallized in the second irradiation step is schematically shown in FIG. Here, the irradiation region R of the laser beam irradiated on the first divided region D1 and the irradiation region R of the laser beam irradiated on the second divided region D2 overlap each other at the ends. In (c), the overlapping portion W is indicated by hatching. On the other hand, the portions not hatched are non-overlapping portions V. Neighboring divided areas D1, D2
Is provided to absorb the position error of the irradiation region R. As a feature of the present invention, (d)
As shown in (1), at least one of the ends where the overlap occurs in the irradiation region R is such that the width WX parallel to the dividing line DL is adjusted to 80% or less of the width VX of the portion where the overlap does not occur. I have. Thereby, the laser beam intensity between the overlapping portion W and the non-overlapping portion V is relatively adjusted. Alternatively, as shown in (e), the laser beam energy density EW on at least one side of the end where the overlap occurs in the irradiation region R.
Is the laser light energy density E of the portion where no overlap occurs.
V may be controlled to 95% or less. Even in this case, the laser beam intensity between the overlapping portion W and the non-overlapping portion V can be relatively adjusted.

In the embodiment shown in FIG. 1, the irradiation region R of the laser beam is set in a direction perpendicular to the division line DL (Y direction, major axis).
Is formed in a long shape along. In this case, in the first irradiation step, as shown in (a), the laser light is scanned while scanning the irradiation area R along the direction (X direction, short axis) parallel to the division line DL with respect to the first division area D1. Is repeatedly irradiated. In the second irradiation step, as shown in (b), the second divided area D2 is repeatedly irradiated with laser light while scanning the irradiated area R along a direction parallel to the division line DL (overlap irradiation). are doing. As a result, as shown in (c), the irradiation region R of the laser light irradiated to the first divided region D1 and the irradiation region R of the laser light irradiated to the second divided region D2 are long ends. It will be overlapping.
In the overlap irradiation described above, scanning is performed with a feed pitch determined so that long beams overlap in the short axis direction (X direction). The overlap ratio OL indicates how much overlap is applied to the beam width VX in the short axis direction, and OL = (short axis beam width−short axis feed pitch) / short axis beam width × 100%. Is represented. For example, when OL = 90%, the next irradiation area R overlaps the previous irradiation area R by 90%, and the irradiation area R moves by the short axis width by repeating irradiation ten times. Will be.

FIG. 2 is an example of a schematic block diagram showing a laser irradiation apparatus according to the present invention. As shown in the figure, the laser irradiation apparatus adjusts a laser beam 50 oscillated by a laser oscillator 51 to an appropriate energy intensity using an attenuator 52. Of course, the energy intensity may be adjusted to an appropriate one by changing the emission intensity of the laser oscillator 51 without using the attenuator 52. The laser light 50 is shaped into, for example, a long shape and made uniform by the optical system 53 including a homogenizer or the like. At this time, shaping is performed so that the short axis width of the overlapping portion is 80% or less of the maximum short axis width. Alternatively, the energy density of the overlapping portion may be adjusted to be 95% or less of the energy density of the non-overlapping portion. In some cases, it may be shaped so as to satisfy both of them at the same time. The insulating substrate 1 placed on the XY stage 55 in the chamber 54 is irradiated with the laser light 50. Note that a semiconductor thin film 2 to be processed is formed on the insulating substrate 1 in advance. The inside of the chamber 54 is a nitrogen atmosphere, an air atmosphere, another gas atmosphere, or a vacuum atmosphere created by a dry pump or the like. In some cases, the XY stage 55 may be used without using the chamber 54.
The crystallization annealing may be performed only in the air atmosphere.
When a semiconductor thin film 2 made of, for example, amorphous silicon is formed on the insulating substrate 1 by an appropriate method, the amorphous silicon is converted into polycrystalline silicon by irradiation with the laser beam 50.

Referring now to FIG. 3, two methods for measuring the short axis width VX of the long beam will be described. In the first method,
With the laser irradiation apparatus shown in FIG. 2, a total reflection mirror is placed just before the insulating substrate 1 to cut out a long beam. This long beam is taken into a CCD beam profiler. By scanning the CCD beam profiler in the long axis direction of the long beam, all beam profiles can be captured. The captured beam profile can be subjected to image processing to measure the short axis width VX. (A) shows a profile of a long beam created by a CCD beam profiler. Where the short axis width V
X is defined by a half width as shown in (b) on a cross section when the profile of (a) is cut along the XX plane. This short axis width VX varies to some extent depending on the position of the XX cut plane. Here, the maximum value in the range of variation is defined as the short axis width VX.
Is defined. In the second measurement method, the amorphous silicon is actually locally converted into polycrystalline silicon by the laser irradiation apparatus shown in FIG. 2, and observation is performed with an optical microscope or the like using the difference in transmittance between the two. As shown in (c), the short axis width VX is measured from the actual observation image. Although the absolute values of the minor axis width VX obtained by these two measurement methods do not completely match, the present invention uses the minor axis width in the overlapped portion as a percentage from the maximum minor axis width measured by each method. The value of WX is specified, and the difference in the measurement method itself does not matter.

As for the method of measuring the energy density, if an energy meter is attached to the position where the CCD beam profiler for measuring the short axis width is attached, the energy of the beam can be directly measured. By scanning in the long axis direction similarly to the CCD beam profiler, the energy density at each beam position can be measured.

Next, referring to FIGS. 4, 5 and 6, when the energy density of the overlapped portion is set to 95% or less of the energy density of the non-overlapping portion, the crystallinity of the overlapped portion is improved. Explain why. First, the influence of the overlap ratio OL on crystallinity will be described with reference to FIG. In the graph of FIG. 4, the irradiation energy density is plotted on the horizontal axis, and the crystallinity is plotted on the vertical axis. This crystallinity quantifies the uniformity and size of crystal grains obtained by laser annealing, and is represented by an arbitrary memory in the graph. In the graph, C80 represents the crystallinity when the overlap irradiation is performed at OL = 80%, C90 represents the crystallinity at OL = 90%, and C95 represents the crystallinity at OL = 95%. When OL = 80%, the best crystallinity can be obtained by setting the irradiation energy density to 380 mJ / cm ² . When OL = 90%, the optimum irradiation energy density is about 370 mJ / cm ² , and when OL = 95%, the optimum irradiation energy density is about 360 mJ / cm ² . As described above, by increasing the overlap ratio OL from 80% to 90% and further to 95%, the optimum irradiation energy density decreases. Conversely, if the overlap ratio is reduced, a high irradiation energy density is required to obtain good crystallinity. That is, in the graph of FIG. 4, when the overlap ratio is reduced, the optimum irradiation energy density shifts to the right.

Next, the graph of FIG. 5 shows the difference in crystallinity between the superposed portion and the non-superposed portion when using the conventional irradiation method in which the short axis width of the superposed portion is not particularly devised. In the graph, CW represents the crystallinity of the overlapped portion, and CV represents the crystallinity of the non-overlapped portion. The data obtained in this graph is the crystallinity when OL = 95%. Therefore, C95 in FIG. 4 and CV in FIG. 5 match, and the optimum irradiation energy density is 360 mJ / cm ² . On the other hand, when OL = 95%, the overlapping portion C
The optimal irradiation energy density in W is 350 mJ / c
m ² . In other words, the superimposition shifts the optimum irradiation energy density to the left. Here, if the irradiation energy density is set with emphasis on the crystallinity of the non-overlapping portion, the crystallinity of the overlapping portion decreases. This is,
This is the cause of the deterioration of the crystallinity of the superposed portion and the occurrence of image defects. Therefore, in the present invention, laser annealing is performed using an optical system in which the energy density of the superposed portion is reduced to 95% or less of the energy density of the non-superposed portion. FIG. 6 shows the resulting difference in crystallinity between the superposed portion and the non-superposed portion. As is clear from the graph, the overlapped portion and the non-overlaid portion show almost the same peak. This is a factor that lowers the crystallinity by lowering the energy density (shift right),
This is probably due to the fact that the elements shifted to the left by the superposition have just canceled each other. In other words, the number of times of energy irradiation is twice as large in the superimposed portion as in the non-superimposed portion, so that the energy is excessive in this state. Therefore, in the present invention, the balance between the two is achieved by lowering the energy density of the non-overlapping portion than that of the overlapping portion. By the way, the normal irradiation condition is, for example, 350 mJ / c.
m ² . At this time, 95% of the energy is about 330 mJ / cm ² . That is, the difference in energy density between the superposed portion and the non-superposed portion is 20 mJ / cm.
It becomes ² . If the energy density is lower than this, the effect of the present invention cannot be expected.

The width of the short axis of the overlapped portion is set to its maximum value of 80.
The difference in crystallinity between the superimposed portion and the non-overlapping portion when the ratio is set to not more than% also shows substantially the same peak in the superimposed portion and the non-overlapping portion as in the graph of FIG.
This is because the element that shifts to the left by overlapping and the element that shifts to the right due to the reduced overlap ratio of this part due to the shortened short axis width of the overlapping part just cancel each other out. This is probably due to By the way, under normal irradiation conditions, the short axis width is 500
Apply a 95% overlap at about μm. This means a feed pitch of 25 μm. At this time, the width of the short axis of the overlapping portion is set to the maximum value (here, 500 μm) of 80.
%, It is 400 μm. When the overlap ratio of this portion is calculated, it is about 94%. That is, unless the width of the short axis of the overlapped portion is set to 80% or less of the maximum value, the influence on the overlap ratio is almost eliminated, and the effect of the present invention cannot be expected. In the case of a long beam, overlapping portions appear at both ends in the long axis direction. In the present invention, the width of the short axis at both ends is set to 80% or less of the maximum value, or the energy density at both ends is set to 95% or less. However, it is clear that a similar effect can be expected only at one end.

FIG. 7 shows an example of specific means for adjusting the width of the short axis at the end of the long beam to 80% or less. In the laser irradiation apparatus shown in FIG. 2, shaping is performed using an optical system 53 such as a homogenizer, but the short axis profile still has some tails on both sides as shown in FIG. If a sharper profile is required at the end, a physical slit 535 is used. The effect of this is shown in FIG. By using the slit 535 in this manner, a desired short axis width WX can be obtained. By applying the slit 535 to at least one end of the long beam in this way, as shown in FIG.
The width WX of the short axis in the overlapping portion W is changed to the non-overlapping portion V.
Can be set to 80% or less of the maximum short axis width VX in the above.

FIG. 8 shows an example of specific means for controlling the energy density at the end of the long beam to 95% or less. FIG. 8 is an enlarged view of a part of an optical system 53 such as a homogenizer of the laser irradiation apparatus shown in FIG. The homogenizer is the first fly-eye lens 53
1. Second fly-eye lens 532 and condenser lens 53
3, the long beam is made uniform. Here, when the second fly-eye lens 532 is shifted with respect to the first fly-eye lens 531 as shown by an arrow, the overlap on the image plane also shifts, and as a result, a profile with low energy density is obtained at both ends in the major axis direction. Can be By controlling the amount of deviation, it is possible to give the end an energy density of 95% of the maximum value. Depending on the adjustment of the homogenizer and other optical systems, it is also possible to make the energy density of only one of the inner ends at both ends in the long axis direction 95% or less.

FIG. 9 is a schematic plan view showing another example of the method for crystallizing a semiconductor thin film according to the present invention. In this example,
The semiconductor thin film is crystallized using a laser beam having a rectangular irradiation region R instead of a long laser beam.
Also in this example, while dividing the surface of the substrate along the division line DL to define at least the first division region D1 and the second division region D2, the laser beam is shaped into a rectangle and at least each division region D1 is formed.
The irradiation region R of the laser beam is adjusted so that the laser beams 1 and D2 can be partially irradiated. The irradiation region R of the laser beam irradiated on the first divided region D1 and the irradiation region of the laser beam irradiated on the second divided region D2 overlap each other at an end, and the energy density of the laser light at the end where the overlap occurs Is 95 times lower than the energy density of the laser light in the portion where no overlap occurs.
% Or less.

FIG. 10 shows another embodiment of the method for crystallizing a semiconductor thin film according to the present invention. In this example, the substrate 1
Are divided into six divided areas D1 to D6.
On the other hand, the irradiation region R has a size substantially corresponding to each of the divided regions D, and the semiconductor thin film included in each of the divided regions D is crystallized at once by the collective irradiation instead of the overlap irradiation as in the above example. Can be For example, a first irradiation step of irradiating the first divided region D1 with a laser beam to crystallize a semiconductor thin film included in the first divided region D1 is performed, and then applying a laser beam to the second divided region D2. A second irradiation step is performed to crystallize the semiconductor thin film included in the second divided region D2 by collective irradiation. The irradiation region R of the laser beam irradiated on the first divided region D1 and the irradiation region R of the laser beam irradiated on the second divided region D2 overlap each other at the ends, and the laser light of the end W where the overlap occurs is generated. The energy density is 9 times smaller than the energy density of the laser beam in the central portion V where no overlap occurs.
It is controlled to 5% or less.

FIG. 11 is a process chart showing an example of a method for manufacturing a thin film transistor according to the present invention. This shows a method for manufacturing a thin film transistor having a bottom gate structure. First, as shown in (a), Al, Ta, Mo, W, Cr, Cu or an alloy thereof is formed on an insulating substrate 1 made of glass or the like to a thickness of 100 to 200 nm, and is patterned to form a gate electrode 5. Process into

Next, as shown in FIG.
A gate insulating film on the substrate. In this example, the gate insulation
The film is a gate nitride film 3 (SiN_x) / Gate oxide film 4 (S
iO _Two) Was used. The gate nitride film 3 is made of SiH
_FourGas and NH_ThreeUse a gas mixture as the source gas
The film was formed by a plasma CVD method (PCVD method). In addition, Plas
Normal pressure CVD or reduced pressure CVD may be used instead of
No. In this embodiment, the gate nitride film 3 has a thickness of 50 nm.
Deposited. Gate oxidation is performed successively after the formation of the gate nitride film 3.
The film 4 is formed with a thickness of about 200 nm. Further gate acid
Semiconductor thin film made of amorphous silicon continuously on the oxide film 4
The film 2 was formed with a thickness of about 30 to 80 nm. Two-layer structure
Of the gate insulating film and the amorphous semiconductor thin film 2
A continuous film was formed without breaking the vacuum system. With the above film formation, plasma C
When the VD method is used, at a temperature of 400 to 450 ° C.
Heat treatment for about 1 hour in nitrogen atmosphere
The hydrogen contained in the thin film 2 is released. So-called dehydration
Elementary annealing is performed. Next, a laser beam 50 is irradiated,
The crystalline semiconductor thin film 2 is crystallized. As the laser beam 50
An excimer laser beam can be used. So-called
Laser annealing uses semiconductors at process temperatures below 600 ° C
It is a powerful means for crystallizing thin films. In this embodiment
Converts the pulsed laser beam 50 into an amorphous semiconductor
The thin film 2 is irradiated for crystallization. Specifically, the substrate 1
Divided into at least the first and second divided areas
While defining the area, the laser beam 50 is shaped and at least
Irradiation of laser beam 50 so that each divided area can be partially irradiated
Preparatory process to adjust the projection area and the first divided area
By irradiating the laser beam 50 at least once, the laser beam 50 is included in the first divided region.
A first irradiation step for crystallizing the semiconductor thin film 2
The laser beam 50 is irradiated at least once on the divided region of
The second step for crystallizing the semiconductor thin film 2 included in the second divided region
And performing two irradiation steps. At this time, the first divided area is irradiated
Irradiates the irradiated area of the laser beam 50 and the second divided area
The irradiated areas of the laser beam 50 overlap each other at the ends.
At least the end where the overlap occurs in the irradiation area
The energy density of the laser beam 50 on one side is
Compared to the energy density of the laser beam 50 in the area where
The total is controlled to 95% or less.

As shown in FIG. 2C, SiO ₂ is formed on the polycrystalline semiconductor thin film 2 crystallized in the previous step to a thickness of about 100 nm to 300 nm by, for example, a plasma CVD method. This SiO ₂ is patterned into a predetermined shape and processed into a stopper film 16. In this case, the stopper film 16 is patterned so as to be aligned with the gate electrode 5 using the back surface exposure technique. The portion of the polycrystalline semiconductor thin film 2 located immediately below the stopper film 16 is protected as a channel region Ch. Subsequently, impurities (for example, P + ions) are implanted into the semiconductor thin film 2 by ion doping using the stopper film 16 as a mask to form an LDD region. The dose at this time is, for example, 6 × 10 ^{12 to} 5 × 10 ¹³ / cm ^2.
It is. Further, the stopper film 16 and the LDD on both sides thereof
After patterning a photoresist so as to cover the region, impurities (for example, P + ions) are implanted at a high concentration using the photoresist as a mask to form a source region S and a drain region D. For example, ion doping can be used for the impurity implantation. This is to implant impurities by electric field acceleration without applying mass separation. In this embodiment, the impurities are implanted at a dose of about 1 × 10 ¹⁵ / cm ² to form the source region S and the drain region D. .
Although not shown, in the case of forming a P-channel thin film transistor, after the region of the N-channel thin film transistor is covered with a photoresist, the impurity is switched from P + ions to B + ions and the dose is about 1 × 10 ¹⁵ / cm ^2. Ion doping.

Thereafter, the impurities implanted in the polycrystalline semiconductor thin film 2 are activated. Note that also here, laser activation annealing using an excimer laser light source is performed. That is,
The glass substrate 1 is irradiated with a pulse of an excimer laser while scanning, thereby activating the impurities implanted in the polycrystalline semiconductor thin film 2.

Finally, as shown in FIG. 2D, a film of SiO ₂ is formed to a thickness of about 200 nm to form an interlayer insulating film 6. After the formation of the interlayer insulating film 6, SiN _x is applied for about 2
The passivation film (cap film) 8 is formed to a thickness of 00 to 400 nm. At this stage, heat treatment at about 350 ° C. is performed for one hour in an atmosphere of nitrogen gas, forming gas, or vacuum to diffuse hydrogen atoms contained in the interlayer insulating film 6 into the semiconductor thin film 2. Thereafter, a contact hole is opened, and Mo, Al, or the like is sputtered with a thickness of 200 to 400 nm, and then patterned into a predetermined shape to process the wiring electrode 7. Further, after a flattening layer 10 made of an acrylic resin or the like is applied with a thickness of about 1 μm, a contact hole is opened. ITO or IX on the flattening layer 10
After sputtering a transparent conductive film made of O or the like, it is patterned into a predetermined shape and processed into the pixel electrode 11.

Referring to FIG. 12, another example of the thin film transistor according to the present invention will be described. First, as shown in (a),
Two-layer base film 16 serving as a buffer layer on insulating substrate 1
a and 16b are continuously formed by a plasma CVD method. The first underlayer 16a is made of SiN _x and has a thickness of 1.
00 to 200 nm. Also, the second-layer underlayer 16b
Is made of SiO ₂ , and its film thickness is also 100 nm to 200 nm. This base film 16b made of SiO ₂
A semiconductor thin film 2 made of polycrystalline silicon is formed to a thickness of 40 to 100 nm by low pressure chemical vapor deposition (LP-CVD). Subsequently, Si + ions are injected into the semiconductor thin film 2 by accelerating the electric field with an ion implantation apparatus or the like, thereby amorphizing the polycrystalline silicon. Instead of forming a polycrystalline silicon film and amorphizing it, a low pressure chemical vapor deposition method (LP
The semiconductor thin film 2 made of amorphous silicon may be deposited by a (CVD method), a plasma CVD method, a sputtering method, or the like.

Thereafter, the semiconductor thin film 2 is irradiated with a laser beam 50 by using the laser irradiation apparatus shown in FIG. 2 to perform crystallization. Specifically, the surface of the substrate 1 is sectioned along the dividing line to define at least the first and second divided regions, while shaping the laser beam 50 so that at least each of the divided regions can be partially irradiated. A preparatory step for adjusting the irradiation area of the laser beam 50; and a step of repeatedly scanning the irradiation area with respect to the first division area in a direction parallel to the division line.
A first irradiation step of irradiating the semiconductor thin film 2 included in the first divided region by irradiating the first divided region with a laser beam while scanning the irradiated region with respect to the second divided region in a direction parallel to the division line. A second irradiation step of irradiating light 50 to crystallize the semiconductor thin film 2 included in the second divided region. At this time, the irradiation region of the laser beam 50 irradiated to the first divided region and the irradiation region of the laser beam 50 irradiated to the second divided region overlap each other at an end portion, and overlap occurs in the irradiation region. At least one of the ends has a width dimension parallel to the dividing line of 80% as compared to the width dimension of the non-overlapping part.
It has been adjusted below.

Subsequently, as shown in FIG.
Semiconductor thin film 2 made of polycrystalline silicon
Pattern in the shape of a letter. On top of this, a plasma CVD method,
Atmospheric pressure CVD, Low pressure CVD, ECR-CVD, Spa
SiO_Two Is grown from 50 to 400 nm,
The gate insulating film 4 is used. If necessary here, Vth
And implant B + ions, for example.
Dose 0.5 × 10 ¹²~ 4 × 10¹²/ Cm^Two About
It is injected into the semiconductor thin film 2. The acceleration voltage in this case is 80K
It is about eV. In addition, this Vth ion implanter
The operation may be performed before forming the gate insulating film 4. Next
Al, Ti, Mo, W, T
a, doped polycrystalline silicon, etc., or a combination thereof
Gold is deposited to a thickness of 200 to 800 nm and has a predetermined shape.
To form a gate electrode 5. Then P +
Semiconductor thin film 2 by ion implantation using mass separation
To provide an LDD region. This ion implantation
Is performed on the entire surface of the insulating substrate 1 using the electrode 5 as a mask.
U. Dose amount is 6 × 10¹²~ 5 × 10¹³/ Cm^Two In
You. The channel region C located immediately below the gate electrode 5
h is protected, Vth ion implantation
B + ions pre-implanted with
You. After ion implantation into the LDD region, the gate electrode 5
A resist pattern is formed to cover the periphery, and P +
Non-mass separation type ion shower doping method
High concentration implantation to form source region S and drain region D
To achieve. The dose in this case is, for example, 1 × 10¹⁵/ Cm
^Two It is about. The source region S and the drain region D
For the formation, a mass separation type ion implantation apparatus may be used. This
After that, the activation process of the dopant injected into the semiconductor thin film 2 is performed.
Do the work. This activation process is performed by laser annealing.
be able to.

Finally, as shown in (c), an interlayer insulating film 6 made of PSG or the like is formed so as to cover the gate electrode 5. After opening a contact hole in the interlayer insulating film 6, Al—Si or the like is formed by sputtering, patterned into a predetermined shape, and processed into a wiring electrode 7. A passivation film (cap film) 8 is formed by depositing SiN _x to a thickness of about 200 to 400 nm by a plasma CVD method so as to cover the wiring electrode 7. At this stage, annealing is performed in a nitrogen gas at a temperature of 350 ° C. for about one hour to diffuse the hydrogen contained in the interlayer insulating film 6 into the semiconductor thin film 2. A so-called hydrogenation treatment is performed to improve the characteristics of the thin film transistor. After a flattening layer 10 made of acrylic resin or the like is applied on the passivation film 8 to a thickness of about 1 μm, a contact hole is opened in the flattening layer 10. A transparent conductive film made of ITO, IXO, or the like is sputtered on the flattening layer 10, patterned into a predetermined shape, and processed into the pixel electrode 11.

Finally, an example of an active matrix type display device using thin film transistors manufactured according to the present invention will be described with reference to FIG. As shown, the display device has a panel structure including a pair of insulating substrates 101 and 102 and an electro-optical material 103 held between the two. As the electro-optical material 103, for example, a liquid crystal material is used. On the lower insulating substrate 101, a pixel array section 104 and a drive circuit section are integrally formed. The drive circuit is divided into a vertical scanner 105 and a horizontal scanner 106. Further, a terminal portion 107 for external connection is formed at an upper end of a peripheral portion of the insulating substrate 101. The terminal unit 107 is connected to the vertical scanner 105 and the horizontal scanner 1 via a wiring 108.
06. A row-shaped gate wiring 109 and a column-shaped signal wiring 110 are formed in the pixel array unit 104. A pixel electrode 111 and a thin film transistor 112 for driving the pixel electrode 111 are formed at the intersection of the two wires. The gate electrode of the thin film transistor 112 is
9 and the drain region is connected to the corresponding pixel electrode 111
, And the source region is connected to the corresponding signal wiring 110. The gate wiring 109 is connected to the vertical scanner 105, while the signal wiring 110 is connected to the horizontal scanner 106. The thin film transistor 112 for switchingly driving the pixel electrode 111 and the thin film transistors included in the vertical scanner 105 and the horizontal scanner 106 are manufactured according to the present invention. Further, in addition to the vertical scanner and the horizontal scanner, a video driver and a timing generator can also be integrated and formed in the insulating substrate 101.

[0035]

As described above, according to the present invention,
In the method of crystallizing a semiconductor thin film using laser light, the energy density of the laser light in the overlapping portion is controlled to be 95% or less of the energy density of the laser light in the non-overlapping portion,
Alternatively, a uniform polycrystalline semiconductor thin film can be obtained over the entire surface of a large-area substrate by controlling the width of the irradiation region of the overlapping portion to be 80% or less of the width of the irradiation region of the non-overlapping portion. Even if the size of the laser light source or the optical system of the laser irradiation device used for crystallization is small, a display device having a large area can be manufactured, and the effect is very large.

[Brief description of the drawings]

FIG. 1 is a schematic plan view showing a method for crystallizing a semiconductor thin film according to the present invention.

FIG. 2 is a block diagram showing an overall configuration of a laser irradiation apparatus according to the present invention.

FIG. 3 is a schematic diagram for explaining a definition of a short axis width of a long beam.

FIG. 4 is a graph showing a relationship between laser beam irradiation energy density and crystallinity.

FIG. 5 is a graph showing the relationship between laser beam irradiation energy density and crystallinity.

FIG. 6 is a graph showing a relationship between laser beam irradiation energy density and crystallinity.

FIG. 7 is an explanatory view of a main part of a laser irradiation apparatus according to the present invention.

FIG. 8 is an explanatory view of a main part of a laser irradiation apparatus according to the present invention.

FIG. 9 is a plan view showing another embodiment of the method for crystallizing a semiconductor thin film according to the present invention.

FIG. 10 is a plan view showing another example of the method for crystallizing a semiconductor thin film according to the present invention.

FIG. 11 is a manufacturing process diagram showing a thin film transistor according to the present invention.

FIG. 12 is a manufacturing process diagram showing a thin film transistor according to the present invention.

FIG. 13 is a schematic perspective view showing a display device according to the present invention.

FIG. 14 is an explanatory view showing a conventional method for crystallizing a semiconductor thin film.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Insulating substrate, 2 ... Semiconductor thin film, 4 ... Gate oxide film, 5 ... Gate electrode, 11 ... Pixel electrode,
50: laser light, 51: laser oscillator, 52
..Attenuators, 53, optical systems such as homogenizers,
55: stage, DL: dividing line, D1: first dividing region, D2: second dividing region, R: irradiation region, W: overlapping portion, V ... Non-overlapping part

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hisao Hayashi 50st, Estee Elsidi Co., Ltd. 50 Ogawakamifunaki, Higashiura-cho, Chita-gun, Aichi Prefecture No. 35 F-term in Sony Corporation (reference) GG52 HJ04 HJ13 HJ23 HL03 HL04 HM15 NN02 NN12 NN23 NN27 NN35 PP03 PP05 PP06 PP35 QQ25

Claims (10)

[Claims] 1. A semiconductor thin film previously formed on a substrate is irradiated with a laser beam for crystallization, and the surface of the substrate is divided into regions to define at least a first and a second divided region. A preparatory step of adjusting the irradiation area of the laser light so as to shape the light and at least partially irradiate each of the divided areas; and irradiating the first divided area with the laser light at least once to form the first A first irradiation step of crystallizing a semiconductor thin film included in the divided region; and a second irradiation step of irradiating the second divided region with laser light at least once to crystallize the semiconductor thin film included in the second divided region. In the method for crystallizing a semiconductor thin film including two irradiation steps, the irradiation region of the laser beam irradiated on the first divided region and the irradiation region of the laser light irradiated on the second divided region overlap each other at an end portion. Overlap in the irradiated area At least the energy density of the laser beam at one side, the crystallization method of a semiconductor thin film characterized in that it is controlled to 95% or less compared with the energy density of the laser beam portions causing no overlapping parts. 2. The preparation step adjusts an irradiation area of the laser beam into a long shape along a predetermined long axis, and the first irradiation step performs a short axis orthogonal to the long axis on the first divided area. Repeatedly irradiating the laser light while scanning the irradiation area along, the second irradiation step repeatedly irradiates the laser light while scanning the irradiation area along the short axis to the second divided area as well, The irradiation region of the laser beam irradiated to the one divided region and the irradiation region of the laser beam irradiated to the second divided region are overlapped at the long-side end portion of the elongated shape. The crystallization method of a semiconductor thin film according to the above. 3. A semiconductor thin film previously formed on a substrate is irradiated with a laser beam to perform crystallization, so that the surface of the substrate is sectioned along a dividing line to define at least first and second divided regions. On the other hand, a preparation step of shaping the laser beam and adjusting the irradiation region of the laser beam so that at least each of the divided regions can be partially irradiated; A first irradiation step of repeatedly irradiating a laser beam while scanning to crystallize a semiconductor thin film included in the first divided region; and a direction in which the irradiated region is parallel to the divided line with respect to the second divided region. A second irradiation step of repeatedly irradiating a laser beam while scanning to crystallize a semiconductor thin film included in the second divided region, wherein the first divided region is irradiated with the first divided region. Laser light irradiation area and second Irradiation region of laser light applied to the split region are overlapped at the ends to each other, at least one end portion overlapping occurs in the irradiation region,
A method for crystallizing a semiconductor thin film, wherein a width dimension parallel to the dividing line is adjusted to 80% or less of a width dimension of a portion where no overlap occurs. 4. The preparation step adjusts an irradiation area of the laser beam into an elongated shape along a direction orthogonal to the division line, and the first irradiation step performs the first division area on the first division area with the division line. While repeatedly irradiating the laser beam while scanning the irradiation area along the parallel direction, the second irradiation step scans the irradiation area along the direction parallel to the division line for the second division area. Laser light is repeatedly irradiated, and the irradiation area of the laser light applied to the first divided area and the irradiation area of the laser light applied to the second divided area are overlapped at the end of the elongated shape. The method for crystallizing a semiconductor thin film according to claim 3, wherein 5. A semiconductor thin film previously formed on a substrate is irradiated with a laser beam to crystallize the semiconductor thin film. At least first and second divided regions are defined by dividing the surface of the substrate into regions. Means for adjusting the laser light irradiation area so that at least each of the divided areas can be partially irradiated by shaping the laser light, and irradiating the laser light once or more to the first divided area. Means for crystallizing the semiconductor thin film included in the first divided region, and further irradiating the second divided region with laser light at least once to crystallize the semiconductor thin film included in the second divided region. In the laser irradiation device provided, the irradiation region of the laser light irradiated to the first divided region and the irradiation region of the laser light irradiated to the second divided region overlap each other at the ends, and within the irradiation region On at least one side of the overlapping end The laser irradiation apparatus characterized in that it has an energy density of the laser beam, a means for controlling 95% or less compared with the laser beam energy density of the portion causing no overlapping kick. 6. A method for irradiating a semiconductor thin film previously formed on a substrate with a laser beam to perform crystallization, wherein a surface of the substrate is partitioned along a dividing line, and at least a first and a second divided region are defined. Means for adjusting the laser light irradiation area so that at least each of the divided areas can be partially irradiated by shaping the laser light, a direction in which the irradiation area is parallel to the division line with respect to the first divided area. The semiconductor thin film included in the first divided region is crystallized by repeatedly irradiating a laser beam while scanning, and the irradiation region is repeatedly scanned with respect to the second divided region in a direction parallel to the dividing line. Means for irradiating a laser beam and crystallizing a semiconductor thin film included in the second divided region, wherein the irradiation region of the laser beam irradiated to the first divided region and the second Irradiation of laser light applied to divided areas The regions overlap each other at the ends, and at least one of the ends where the overlap occurs in the irradiation area is such that the width dimension parallel to the dividing line is 80% or less of the width dimension of the non-overlapping part. A laser irradiation apparatus, characterized in that the laser irradiation apparatus has means for adjusting the distance. 7. A thin film transistor having a stacked structure including a semiconductor thin film, a gate insulating film overlaid on one surface thereof, and a gate electrode overlaid on the semiconductor thin film via the gate insulating film, wherein the semiconductor thin film is Amorphous silicon or polycrystalline silicon having a relatively small particle size is formed on a substrate, and then irradiated with laser light to be crystallized into polycrystalline silicon having a relatively large particle size. After dividing the area to define at least the first and second divided areas, the laser light is shaped and the irradiation area of the laser light is adjusted so that at least each of the divided areas can be partially irradiated. Irradiating the divided region one or more times with laser light to crystallize the semiconductor thin film included in the first divided region, and further irradiating the second divided region one or more times with laser light to Included in the divided area The semiconductor thin film is crystallized, and the irradiation area of the laser beam applied to the first divided area and the irradiation area of the laser light applied to the second divided area are overlapped at the ends. And that the laser beam is crystallized by controlling the energy density of the laser beam on at least one side of the edge where the overlap occurs in the irradiation region to 95% or less of the energy density of the laser beam on the portion where the overlap does not occur. Characteristic thin film transistor. 8. A thin film transistor having a stacked structure including a semiconductor thin film, a gate insulating film overlaid on one surface thereof, and a gate electrode overlaid on the semiconductor thin film via the gate insulating film, wherein the semiconductor thin film is Amorphous silicon or polycrystalline silicon having a relatively small particle size is formed on a substrate, and then irradiated with laser light to be crystallized into polycrystalline silicon having a relatively large particle size. While defining along the dividing line and defining at least the first and second divided areas, after adjusting the irradiation area of the laser light so as to be able to partially irradiate at least each divided area by shaping the laser light, A laser beam is repeatedly irradiated on the first divided region while scanning the irradiation region in a direction parallel to the division line to crystallize a semiconductor thin film included in the first divided region, and further a second divided region is formed. To The semiconductor thin film included in the second divided region is crystallized by repeatedly irradiating a laser beam while scanning the irradiated region in a direction parallel to the division line, and is irradiated to the first division region. After the irradiation region of the laser beam and the irradiation region of the laser beam irradiated to the second divided region overlap each other at the ends, at least one of the ends where the overlapping occurs in the irradiation region is at least one of the division line. A thin film transistor characterized in that the parallel width dimension is adjusted to be 80% or less of the width dimension of a portion where no overlap occurs, and the thin film transistor is crystallized. 9. A semiconductor device comprising: a pair of substrates joined to each other via a predetermined gap; and an electro-optical material held in the gap;
A counter electrode is formed on one substrate, a pixel electrode and a thin film transistor for driving the pixel electrode are formed on the other substrate, and the thin film transistor is formed with a semiconductor thin film and a gate electrode which is superposed on one surface thereof via a gate insulating film. In the display device formed by, in the semiconductor thin film, after forming amorphous silicon or polycrystalline silicon having a relatively small particle size on the other substrate,
A laser beam is irradiated to crystallize into polycrystalline silicon having a relatively large particle diameter. The surface of the other substrate is divided into regions to define at least the first and second divided regions, while the laser light After adjusting the irradiation region of the laser beam so that at least each of the divided regions can be partially irradiated, the first divided region is irradiated with the laser light at least once to the first divided region. A semiconductor thin film included in the second divided region is crystallized, and the semiconductor thin film included in the second divided region is crystallized by irradiating the second divided region with laser light at least once. The irradiation region of the laser beam irradiated to the laser beam and the irradiation region of the laser beam irradiated to the second divided region overlap each other at the ends, and then the laser light on at least one side of the end where the overlap occurs in the irradiation region Energy density Display device comprising control to those that have been crystallized with 95% compared with the energy density of the laser beam portion does not occur below. 10. A semiconductor device comprising: a pair of substrates joined to each other with a predetermined gap therebetween; and an electro-optical material held in the gap. An opposing electrode is formed on one of the substrates, and a pixel is formed on the other substrate. An electrode and a thin film transistor for driving the electrode are formed, and the thin film transistor is a display device including a semiconductor thin film and a gate electrode stacked on one surface thereof with a gate insulating film interposed therebetween, wherein the semiconductor thin film is the other of the other. After forming amorphous silicon or polycrystalline silicon with a relatively small particle size on the substrate,
A laser beam is irradiated to crystallize the polycrystalline silicon having a relatively large particle size, and the surface of the other substrate is divided along a dividing line to define at least first and second divided regions. After shaping the laser beam and adjusting the irradiation region of the laser beam so that at least each of the divided regions can be partially irradiated, the irradiation region is scanned with respect to the first divided region in a direction parallel to the dividing line. While irradiating the laser light repeatedly, the semiconductor thin film included in the first divided region is crystallized, and further the laser light is repeatedly irradiated on the second divided region while scanning the irradiated region in a direction parallel to the dividing line. Irradiating the semiconductor thin film included in the second divided region with crystallization, and irradiating the laser light irradiated to the first divided region and the laser light irradiated to the second divided region Areas overlap each other at the edges In addition, at least one of the ends where the overlap occurs in the irradiation region is crystallized by adjusting the width dimension parallel to the dividing line to be 80% or less of the width dimension of the part where the overlap does not occur. A display device characterized in that: