JP2008288514A - Method of crystallizing semiconductor thin film, method of manufacturing display device, thin-film transistor substrate, and display device provided with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve productivity by efficiently utilizing laser light in laser crystallization of a semiconductor thin film, and further by suppressing equipment cost increase, throughput deterioration, and the like. <P>SOLUTION: The method of crystallizing a semiconductor thin film includes a step of preparing a semiconductor thin film, a step of scanning a laser beam while irradiating the semiconductor thin film with the laser beam, and a step of scanning the laser beam while irradiating the semiconductor thin film with the laser beam in such a way that a side edge portion of the irradiated region formed by having been irradiated with the laser beam is doubly irradiated by a predetermined width. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for crystallizing a semiconductor thin film, a method for manufacturing a display device, a thin film transistor substrate, and a display device including the same.

  Thin film transistors (TFTs) are widely used as switching elements in active matrix display devices (for example, liquid crystal display devices and organic EL display devices). For example, an active matrix type liquid crystal display device has one or more TFTs corresponding to each of hundreds of thousands or more of pixel electrodes arranged in a matrix, and charges supplied to the pixel electrodes are controlled by the TFTs. The

  A thin film transistor used as a switching element of a display device includes an active layer made of polycrystalline silicon, and a driving circuit is formed on the same substrate in addition to the switching element.

  As a method for producing such a polycrystalline semiconductor thin film, there is a method (laser annealing method) in which an amorphous semiconductor film is crystallized by irradiating it with laser light and melting and solidifying it. As a laser annealing method, an excimer laser annealing method in which an amorphous silicon thin film is irradiated with a short pulse laser of about 10 to 100 ns called an excimer laser to obtain a polycrystalline silicon thin film is formed on a large glass substrate or the like. Since this is a low-temperature process capable of forming a polycrystalline silicon thin film at a low temperature below the strain point of the substrate, mass production of TFTs using the polycrystalline silicon thin film has recently been realized by this method.

As such a technique, for example, Patent Document 1 discloses p-ch. A semiconductor thin film serving as a TFT channel and n-ch. A semiconductor thin film that is formed by laser annealing with different laser intensities is disclosed.
Japanese Patent Laid-Open No. 06-252398

  In general, when a pixel portion and a peripheral circuit such as a display driving driver are formed over a semiconductor film on the same substrate, the region in which the peripheral circuit is formed has a mobility compared to the region in which the pixel portion is formed. There may be cases where semiconductor characteristics having good or different performance such as high are required. If this is to be realized by the conventional laser crystallization method as described above, it is necessary to increase the number of laser spot irradiations only in the peripheral circuit formation region when laser crystallization of the semiconductor film. There arises a problem that costs increase and a problem that throughput deteriorates.

  The present invention has been made in view of such various points, and the object of the present invention is to efficiently use laser light in laser crystallization of a semiconductor thin film. It is to improve productivity by suppressing deterioration and the like.

  The method for crystallizing a semiconductor thin film according to the present invention includes a step of preparing a semiconductor thin film, a step of scanning the semiconductor thin film with laser light while irradiating the semiconductor thin film, and an irradiation region formed by laser light irradiation. And a step of scanning the laser beam while irradiating the semiconductor thin film with the laser beam so as to overlap the side edge portion by a predetermined width.

Further, in the method for crystallizing a semiconductor thin film according to the present invention, the laser beam is an excimer laser, a second harmonic of an Nd: YAG laser, a second harmonic of an Nd: YVO ₄ laser, or a second harmonic of an Nd: YLF laser. Wave, Nd: second harmonic of glass laser, Yb: second harmonic of YAG laser, Yb: second harmonic of glass laser, Ar ion laser, Ti: second harmonic of sapphire laser, and Dye laser You may include at least 1 sort (s) chosen from the group.

  The method for crystallizing a semiconductor thin film according to the present invention is formed by preparing a semiconductor thin film, scanning the laser light in a predetermined direction while irradiating the semiconductor thin film with laser light, and irradiating the laser light. Irradiating the semiconductor thin film with laser light so as to overlap the side edge portion of the irradiated region by a predetermined width, and scanning the laser light in parallel with the predetermined direction along the side edge of the irradiated region. Features.

  The display device manufacturing method according to the present invention includes a step of preparing a semiconductor thin film, a first step of scanning the semiconductor thin film with laser light while irradiating the semiconductor thin film, and an irradiation region formed by laser light irradiation. A second step of scanning the semiconductor thin film while irradiating the semiconductor thin film with a laser beam so as to overlap a side edge portion of the first display element; and a region of the semiconductor thin film irradiated with the laser light in the first step. And a fourth step of forming a second display element in a region of the semiconductor thin film irradiated with the laser beam so as to overlap in the second step.

  A thin film transistor substrate according to the present invention includes a substrate, and a plurality of first island-shaped portions each having a first semiconductor thin film that is provided on the substrate and has a predetermined semiconductor characteristic and having a first display element formed thereon, A plurality of second island-shaped portions having a second semiconductor thin film having a semiconductor characteristic different from that of the first semiconductor thin film provided on the substrate and having the second display element are in contact with the first semiconductor thin film and the second semiconductor thin film And a third island-shaped portion arranged side by side on the substrate.

  In the thin film transistor substrate according to the present invention, the second island portion may include a second semiconductor thin film having a surface roughness different from that of the first semiconductor thin film.

  In the thin film transistor substrate according to the present invention, the second semiconductor thin film may have higher charge mobility than the first semiconductor thin film.

  In the thin film transistor substrate according to the present invention, the second semiconductor thin film may have a surface roughness larger than that of the first semiconductor thin film.

  A display device according to the present invention includes the above-described thin film transistor substrate.

  According to the present invention, laser light can be efficiently used in laser crystallization of a semiconductor thin film, and further, productivity can be improved by suppressing an increase in cost of the apparatus, deterioration in throughput, and the like.

  Hereinafter, a method for crystallizing a semiconductor thin film, a method for manufacturing a display device, a thin film transistor substrate, and a display device including the same according to embodiments of the present invention will be described in detail with reference to the drawings. The present invention is not limited to the following embodiment.

  In this embodiment, a case where an amorphous silicon thin film (a-Si layer) in a display device is subjected to laser crystallization processing will be described.

  The laser crystallization method according to the embodiment of the present invention can be performed using, for example, a laser crystallization apparatus 10 as shown in FIG. The laser crystallization apparatus 10 includes a pulse laser oscillator 11, a reflecting mirror 12, an optical system 13, a processing stage 14, and a system control unit 15.

  A pulsed laser oscillator 11 that oscillates a pulsed laser beam is provided at the top of the laser crystallization apparatus 10 and has a laser light source 16. If necessary, a phase modulation element 17 or the like may be provided downstream of the laser light source 16.

  The laser light source 16 outputs a pulsed laser beam having energy sufficient to crystallize the semiconductor film to be processed.

The laser light is preferably, for example, a XeCl excimer laser light with a wavelength of 308 nm or a KrF excimer laser light with a wavelength of 248 nm. In addition, the second harmonic of the Nd: YAG laser, the second harmonic of the Nd: YVO ₄ laser, the second harmonic of the Nd: YLF laser, the second harmonic of the Nd: glass laser, and the second harmonic of the Yb: YAG laser. It may include at least one selected from the group consisting of harmonic, Yb: second harmonic of glass laser, Ar ion laser, second harmonic of Ti: sapphire laser, and Dye laser.

  The laser light source 16 is a pulse oscillation type, and its oscillation frequency is, for example, 100 to 300 Hz. The pulse width is a half width, for example, 20 to 100 nsec.

  The reflecting mirror 12 that reflects the pulse laser beam 20 from the pulse laser oscillator 11 is provided on the optical path of the pulse laser beam 20 emitted from the pulse laser oscillator 11 so as to be inclined at a predetermined angle.

  The optical system 13 is provided on the optical path of the pulsed laser light 20 reflected by the reflecting mirror 12. The optical system 13 is composed of a plurality of cylindrical lenses for irradiating the pulsed laser light 20 with, for example, shaping it into a rectangular shape, a square shape, an elliptical shape or the like.

  The processing stage 14 is provided at the lowermost part of the laser crystallization apparatus 10. The processing stage 14 is connected to the system control unit 15.

  The system control unit 15 is on the side of the laser crystallization apparatus 10 and is connected to the processing stage 14 and the pulse laser oscillator 11.

  Next, the function of the laser crystallization apparatus 10 will be described.

  The laser light source 16 of the pulse laser oscillator 11 oscillates the pulse laser beam 20 in response to a signal transmitted from the system control unit 15 and reflects the pulse laser beam 20 with the reflecting mirror 12.

  The pulsed laser beam 20 reflected by the reflecting mirror 12 enters the optical system 13. The pulsed laser light 20 is focused by a plurality of cylindrical lenses in the optical system 13, shaped into laser light 21, and irradiated onto the semiconductor thin film.

  The system control unit 15 moves the processing stage 14 in the plane direction according to the timing of irradiation of the laser light 21 to the semiconductor thin film.

(Semiconductor thin film crystallization method)
Next, a method for crystallizing a semiconductor thin film using the laser crystallization apparatus 10 will be described. Here, a case where an amorphous silicon film is used as a semiconductor film and crystallized to manufacture a polycrystalline semiconductor film will be described.

  First, an amorphous silicon film having a thickness of, for example, about 500 mm is formed on a substrate formed in a size of, for example, 680 mm × 880 mm. This step is a step of forming an amorphous silicon film on almost the entire surface of a substrate (for example, a glass substrate) constituting the display panel, and is performed by a known method.

  Next, the substrate 30 on which the amorphous silicon film is formed is placed on the processing stage 14 of the laser crystallization apparatus 10.

  Next, a pulse laser beam 20 is oscillated from the laser light source 16 of the pulse laser oscillator 11 by transmitting a signal from the system control unit 15.

  Next, the oscillated pulse laser beam 20 is reflected by the reflecting mirror 12 and travels toward the optical system 13, is shaped into a laser beam 21 by the optical system 13, and is irradiated onto the amorphous silicon film of the substrate 30.

  After irradiating the amorphous silicon film of the substrate 30 with the laser light 21, the processing stage 14 is moved in the plane direction by the system control unit 15. The moving direction is the width direction of the laser beam 21.

  When the amorphous silicon film on the substrate 30 irradiated with the laser beam 21 is moved, the system controller 15 sends a signal to the pulse laser oscillator 11 in the same manner to oscillate the pulse laser beam 20. At this time, as shown in FIG. 2, the amorphous silicon film of the substrate 30 is crystallized in order toward a predetermined direction (from top to bottom in FIG. 2) of the laser light 21 irradiated from one end.

  Subsequently, as shown in FIG. 2, the processing stage 14 is moved by the system control unit 15 and is formed by irradiation with the laser beam 21 with a position parallel to the irradiation start position of the previously irradiated laser beam as a start position. The laser beam 21 is irradiated so as to overlap the side edge portion 32 of the irradiated region 31 by a predetermined width.

  Next, the processing stage 14 is moved to irradiate the amorphous silicon film of the substrate 30 while scanning the laser beam 21 along the side edge of the irradiation region 31 in parallel with the predetermined direction.

  As a result, the side edge portion 32 of the irradiation region 31 of the laser light 21 once crystallized is overlapped with a predetermined width on the amorphous silicon film of the substrate 30 and is crystallized again, so that the conventional laser crystallization method is used. In addition, it is not necessary to irradiate the laser beams 21 separately. That is, only by scanning the laser beam 21 along the side edge of the irradiation region 31 while irradiating the laser beam 21 so as to overlap the side edge portion 32 of the irradiation region 31 of the laser beam 21 once formed by a predetermined width, A region having higher semiconductor characteristics can be formed.

  In this way, the polycrystalline semiconductor thin film 45 is manufactured by performing the crystallization process by laser irradiation over the entire amorphous silicon film of the substrate 30.

(Manufacturing method of display device)
Next, a method for manufacturing a display device according to an embodiment of the present invention will be described. Here, the liquid crystal display device 40 will be described as an example of the display device.

  First, a semiconductor thin film formed on an insulating substrate such as glass is crystallized as described above to produce a polycrystalline semiconductor thin film 45. At this time, as shown in FIG. 2, the polycrystalline semiconductor thin film 45 includes an irradiation region 31 that is irradiated with the laser beam 21 by one scanning, and a region (side) irradiated with the laser beam 21 superimposed thereon. The edge portions 32) are alternately formed in stripes.

  Next, a display element (first display element) constituting a pixel portion such as a TFT is formed in the irradiation region 31 (first semiconductor thin film), and a peripheral circuit is formed in the side edge portion 32 (second semiconductor thin film). A display element (second display element) to be formed is formed.

  Here, the polycrystalline semiconductor thin film 45 is etched in a matrix form as shown in FIG. 3, and each constitutes a pixel part 50 (first island part) and a peripheral circuit part 51 (second island part). is doing. In addition, on the polycrystalline semiconductor thin film 45, the semiconductor thin film 46 that remains without being etched exists on the boundary line 44 between the irradiation region 31 and the side edge portion 32, and the irradiation region 31 and the side edge portion 32 are separated from each other. A region (third island-shaped portion) arranged on the substrate so as to be in contact with each other is formed.

  The irradiation region 31 and the side edge portion 32 of the third island portion thus formed have different semiconductor characteristics (for example, charge mobility and surface roughness).

  In general, the side edge portion 32 has a higher charge mobility such as n-channel mobility and p-channel mobility than the irradiation region 31, and crystallization is performed so that the surface roughness is larger than that of the irradiation region 31. There are many, but it is not necessary.

  In the third island portion, the polycrystalline semiconductor thin films having different semiconductor characteristics such as charge mobility and surface roughness are in contact with each other to form a predetermined boundary line.

  The reason why the third island-shaped portion is provided on the polycrystalline semiconductor thin film 45 is that the above-described boundary line can be confirmed, which facilitates process inspection and thin film analysis.

  The boundary line is not limited to be provided between the pixel unit 50 and the peripheral circuit unit 51, and may be formed in the peripheral circuit unit 51. That is, an island-shaped portion provided with both the irradiation region 31 and the side edge portion 32 may be formed by etching, and this may be used as the peripheral circuit portion 51.

  As shown in FIG. 3, only one third island portion may be formed on one thin film transistor substrate 55, and a plurality of third island portions may be formed on the boundary line 44.

  Next, a predetermined process is performed on the substrate 30 to form TFTs and the like.

  Next, a small substrate (thin film transistor substrate 55) is cut out in a rectangular shape from the substrate 30 on which the first display element and the second display element are formed. At this time, the cut-out small substrate includes both thin film transistors including the pixel portion 50 in which the first display element is formed and the peripheral circuit portion 51 in which the second display element is formed.

  Next, the color filter substrate 56 including the color filter 85 and the like is manufactured. At this time, the color filter substrate 56 may be divided into a plurality of small substrates after the color filter 85 and the like are first formed on a large substrate, or small substrates may be individually manufactured from the beginning.

  Next, the thin film transistor substrate 55 and the color filter substrate 56 are bonded together, a liquid crystal material 80 is injected between the substrates, and a polarizing plate 58 and a protective film 59 are formed on the substrate, whereby a liquid crystal display panel 57 is manufactured. . The liquid crystal material may be provided between the substrates by dropping and injecting the liquid crystal material onto the thin film transistor substrate 55 and then bonding the color filter substrate 56 together.

  Next, the liquid crystal display device 40 is manufactured by providing a backlight 70 or the like on the liquid crystal display panel 57.

(Configuration of Liquid Crystal Display Device 40 Using Thin Film Transistor Substrate 55)
Next, the configuration of the liquid crystal display device 40 including the thin film transistor substrate 55 according to the present invention will be described in detail with reference to the drawings.

  As shown in FIG. 4, the liquid crystal display device 40 includes a liquid crystal display panel 57, a backlight 70, and the like.

  As shown in FIG. 5, the liquid crystal display panel 57 includes a thin film transistor substrate 55 and a color filter substrate 56 facing each other, a liquid crystal material 80 provided therebetween, a spacer 81, a peripheral IC 71 formed on the thin film transistor substrate 55, and the like. It consists of

  In the color filter substrate 56, a color filter 85 composed of three primary colors of red (R), green (G) and blue (B) is formed on an insulating substrate made of glass or the like. As the color filter 85, in addition to RGB combinations, cyan, magenta, and yellow complementary colors may be used.

  A counter electrode and an alignment film (not shown) are formed on the color filter 85, respectively. The color filter 85 is provided with a black matrix (light shielding layer) on the outer periphery thereof as a border for obtaining contrast to form a light shielding region.

  The thin film transistor substrate 55 includes pixel TFTs 86 each including a plurality of pixel portions 50 and the like arranged in a matrix on an insulating substrate made of glass or the like. The pixel portion 50 of the pixel TFT 86 is composed of TFTs such as a gate electrode, a source electrode, and a drain electrode (not shown) formed on an insulating substrate, a transparent insulating layer, a pixel electrode, and the like.

  The peripheral circuit TFT 88 is formed on the second semiconductor thin film of the thin film transistor substrate 55.

  In addition, on the polycrystalline semiconductor thin film 45 of the thin film transistor substrate 55, the etching is not performed on the boundary line 44 between the region irradiated with the laser beam 21 by one scanning and the region irradiated with the laser beam 21 in an overlapping manner. The remaining semiconductor thin film 46 exists, and the region (third island shape) arranged in parallel on the substrate so that the region irradiated with the laser beam 21 in one scan and the region irradiated with the laser beam 21 overlapped with each other are in contact with each other. Part). One third island-shaped portion may not be formed on one thin film transistor substrate 55, and a plurality of third island portions may be formed on the boundary line 44.

  The backlight 70 is disposed on the thin film transistor substrate 55 side of the liquid crystal display panel 57. The backlight 70 receives a light emitted from the light source, propagates through the light source and emits it toward the liquid crystal display panel 57, and directs the light emitted from the back surface of the light guide plate toward the light guide plate. And a reflecting plate (both not shown).

  A test for investigating the relationship between the number of pulsed laser shots and semiconductor characteristics was performed using the thin film transistor substrate manufactured by the above-described manufacturing method.

(Production of thin film transistor substrate)
First, a semiconductor thin film was formed on a glass substrate, and the same portion was irradiated 10 times with pulsed laser light as described above. In this manner, the semiconductor thin film was sequentially crystallized, and the same portion was further irradiated 10 times with pulsed laser light so that the peripheral portion of the irradiation region overlapped by a predetermined width as described above. For this reason, the overlapping irradiated region is irradiated 20 times in total.

  Next, a pixel portion composed of a TFT or the like is formed in a region irradiated with the same location 10 times with pulsed laser light, and a peripheral circuit is formed in the region irradiated 20 times, whereby n-channel and p-channel thin film transistor substrates are formed. Each was produced as Example 1.

  Next, a thin film transistor substrate similar to that described above was manufactured by changing the number of times of irradiation with the pulsed laser light to the same portion to 15 times. In other words, n-channel and p-channel thin film transistor substrates are fabricated by forming a pixel portion composed of TFTs or the like in a region irradiated with the same portion 15 times, and forming peripheral circuits in the region irradiated 30 times. 2.

(Test evaluation)
Next, for Examples 1 and 2, the charge mobility, that is, the n-channel mobility and the p-channel mobility, was measured with respect to the number of laser shots, and the results are shown in FIGS. 6 and 7, respectively.

  6 and 7, it can be seen that the charge mobility varies depending on the number of times of irradiation of the pulse laser beam to the same location.

  Moreover, about Example 1 and 2, surface unevenness | corrugation (surface roughness): Ra (nm) was measured with respect to the number of laser shots, respectively, and the result is shown in FIG. It can be seen that the surface irregularities differ depending on the number of times of irradiation of the pulse laser beam to the same location.

  The above results may be equalized or reversed depending on the irradiation conditions of the pulse laser beam and the film configuration of the irradiated substrate, for example, the characteristics and the tendency of the surface roughness.

  For example, the surface unevenness may be equalized even if the characteristics are different by performing a surface flattening treatment after the crystallization.

  From the above results, the thin film transistor substrate manufactured by the manufacturing method described in the embodiment of the present invention has different properties as represented by n channel mobility and p channel mobility, or surface roughness: Ra value. It can be seen that a region (third island-shaped portion) is formed in which the polycrystalline semiconductor thin films are in contact with each other. In the third island-shaped portion, the polycrystalline semiconductor thin films having different crystal states are in contact with each other to form a predetermined boundary line. If there is a difference in surface conditions such as crystal surface irregularities, the boundary line can be easily identified with a microscope, etc., but even if the surface conditions are the same, if the crystallinity is different, use a Raman spectrometer. Even boundary lines can be identified.

(Function and effect)
Next, operational effects will be described.

  The method for crystallizing a semiconductor thin film according to an embodiment of the present invention includes a step of preparing a semiconductor thin film, a step of scanning the semiconductor thin film while irradiating the laser light 21, and an irradiation formed by irradiation of the laser light 21. And scanning with irradiating the semiconductor thin film with the laser beam 21 so as to overlap the side edge portion 32 of the region 31 by a predetermined width.

  According to such a configuration, the semiconductor thin film in which the irradiation with the laser light 21 overlaps can obtain different semiconductor characteristics such as charge mobility as compared with the other regions. It is not necessary to irradiate the light 21 in an overlapping manner. That is, regions having different semiconductor characteristics can be formed simply by scanning while irradiating the laser beam 21 so as to overlap the side edge portion 32 of the irradiation region 31 of the laser beam 21 once formed by a predetermined width. For this reason, for example, a formation region such as a peripheral circuit that needs to have high semiconductor characteristics is provided in a region where the irradiation of the laser light 21 overlaps, and a formation region such as the pixel portion 50 that does not have to have high semiconductor characteristics is provided. By providing the regions, display elements having different properties can be efficiently formed on the same semiconductor substrate.

  As described above, the present invention is useful for a semiconductor thin film crystallization method, a display device manufacturing method, a thin film transistor substrate, and a display device including the same.

1 is a schematic view of a laser crystallization apparatus 10 according to an embodiment of the present invention. It is a figure which shows the mode of crystallization of the amorphous silicon film of the board | substrate 30 which concerns on embodiment of this invention. 3 is a plan view of a polycrystalline semiconductor thin film 45 formed in a matrix on a thin film transistor substrate 55 according to an embodiment of the present invention. FIG. It is sectional drawing of the liquid crystal display device 40 which concerns on embodiment of this invention. It is sectional drawing of the liquid crystal display panel 57 which concerns on embodiment of this invention. It is a graph which shows the laser shot number dependence of the n channel mobility of the n channel thin-film transistor substrate which concerns on Example 1 and 2 of this invention. It is a graph which shows the laser shot number dependence of the p channel mobility of the p channel thin-film transistor substrate which concerns on Example 1 and 2 of this invention. It is a graph which shows the laser shot number dependence of the surface unevenness | corrugation (Ra value) which concerns on Example 1 and 2 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Laser crystallization apparatus 20 Pulse laser beam 21 Laser beam 30 Substrate 31 Irradiation area 32 Side edge portion 40 Liquid crystal display device 44 Boundary line 45 Polycrystalline semiconductor thin film 46 Semiconductor thin film 50 Pixel unit 51 Peripheral circuit unit 55 Thin film transistor substrate 56 Color filter substrate 57 Liquid crystal display panel 71 Peripheral IC
80 Liquid crystal material 81 Spacer 86 Pixel TFT
88 Peripheral circuit TFT

Claims (9)

Preparing a semiconductor thin film; and
Scanning the laser light while irradiating the semiconductor thin film with laser light;
Scanning the laser light while irradiating the semiconductor thin film with laser light so as to overlap with a predetermined width on a side edge portion of an irradiation region formed by the laser light irradiation;
A method for crystallizing a semiconductor thin film comprising: The method for crystallizing a semiconductor thin film according to claim 1,
The laser light includes an excimer laser, a second harmonic of an Nd: YAG laser, a second harmonic of an Nd: YVO ₄ laser, a second harmonic of an Nd: YLF laser, Nd: a second harmonic of a glass laser, Yb A semiconductor thin film containing at least one selected from the group consisting of: second harmonic of YAG laser, Yb: second harmonic of glass laser, Ar ion laser, second harmonic of Ti: sapphire laser, and Dye laser Crystallization method. Preparing a semiconductor thin film; and
Scanning the laser light in a predetermined direction while irradiating the semiconductor thin film with laser light;
While irradiating the semiconductor thin film with laser light so as to overlap a side edge portion of the irradiation region formed by the laser light irradiation, the laser light is directed in the predetermined direction along the side edge of the irradiation region. Scanning in parallel;
A method for crystallizing a semiconductor thin film comprising: Preparing a semiconductor thin film; and
A first step of scanning the semiconductor thin film while irradiating the semiconductor thin film with laser light;
A second step of scanning the laser beam while irradiating the semiconductor thin film with a laser beam so as to overlap a side edge portion of an irradiation region formed by the laser beam irradiation;
A third step of forming a first display element in the region irradiated with the laser light in the first step in the semiconductor thin film;
A fourth step of forming a second display element in a region irradiated with the laser light so as to overlap in the second step in the semiconductor thin film;
A method for manufacturing a display device comprising: A substrate,
A plurality of first island-shaped portions each having a first semiconductor thin film provided on the substrate and having a predetermined semiconductor characteristic on which a first display element is formed;
A plurality of second island-shaped portions each having a second semiconductor thin film provided on the substrate and having a semiconductor characteristic different from that of the first semiconductor thin film on which the second display element is formed;
A third island portion arranged on the substrate so that the first semiconductor thin film and the second semiconductor thin film are in contact with each other;
A thin film transistor substrate comprising: In the thin film transistor substrate according to claim 5,
The second island-shaped portion is a thin film transistor substrate having a second semiconductor thin film having a surface roughness different from that of the first semiconductor thin film. In the thin film transistor substrate according to claim 5,
The second semiconductor thin film is a thin film transistor substrate having higher charge mobility than the first semiconductor thin film. In the thin film transistor substrate according to claim 5,
The second semiconductor thin film is a thin film transistor substrate having a surface roughness larger than that of the first semiconductor thin film.   A display device comprising the thin film transistor substrate according to claim 5.

Images