JP2012248551A - Laser irradiation apparatus - Google Patents

Abstract

An object of the present invention is to perform focus adjustment and beam shape and size adjustment with high accuracy in accordance with displacement of a substrate.
A long-axis slit and a short-axis slit are distinguished for a long-axis and a short-axis, and each is individually variable, so that the focus can be adjusted with high accuracy corresponding to the displacement of the substrate. The beam shape and size can be adjusted.
[Selection] Figure 3

Description

  The present invention relates to a laser irradiation apparatus capable of adjusting the shape and size of laser light applied to an irradiation target.

  Currently, a display device such as a liquid crystal display device or an organic EL display device displays an image by switching pixel transistors (thin film transistors) arranged at the same vertical or horizontal pitch or different pitches. The pixel transistor is formed by crystallizing an amorphous silicon film formed on a substrate such as glass or fused quartz into a polysilicon film.

Hereinafter, a conventional laser irradiation apparatus will be described with reference to FIGS.
6A and 6B are schematic views showing the configuration of an optical system in a conventional laser irradiation apparatus. FIG. 6A is a schematic diagram showing a structure for beam shaping in the major axis direction, and FIG. 6B is a schematic diagram showing a structure for beam shaping in the minor axis direction.

A crystallization apparatus 100 shown in FIGS. 6A and 6B is a conventional crystallization apparatus (see, for example, Patent Document 1).
The crystallization apparatus 100 includes a homogenizing lens 103, a cylindrical lens 108, and a projection lens 105. The homogenizing lens 103 equalizes the intensity of the laser beam 102 emitted from the laser oscillator 101 in the major axis (Y) direction. The cylindrical lens 108 condenses the laser light 102 transmitted through the homogenizing lens 103 on the surface of the slit 104 in the minor axis (X) direction to obtain a laser intensity distribution having a uniform intensity distribution in the minor axis direction. The projection lens 105 transmits the laser beam 102 that passes through the cylindrical lens 108 and projects a mask pattern formed on the surface of the slit 104 onto the thin film silicon 106 to crystallize the thin film silicon 106 made of amorphous-Si (silicon). P-Si (polysilicon). Reference numeral 107 denotes a short axis collimator lens provided between the laser oscillator 101 and the homogenizing lens 103.

  Here, when the opening distance of the slit 104 is L, the distance between the slit 104 and the projection lens 105 is A, and the distance between the projection lens 105 and the thin film silicon 106 is B, the long-axis beam size on the thin film silicon 106 is L * B / A. Further, when the laser beam is irradiated, the laser beam 102 is irradiated in a state where the substrate such as the thin film silicon 106 is held. Therefore, the substrate surface position may be displaced due to bending or warping of the substrate. In order to adjust the focal point without changing the beam size on the substrate in response to such a displacement of the substrate, conventionally, the positions of the projection lens 105, the thin film silicon 106, etc. are moved, and the distances A and B are changed. Was changing.

JP 2007-115841 A JP 2007-48794 A JP 2006-32843 A

  However, with the recent increase in the size of display devices and the miniaturization of pixels, the influence of the displacement of the substrate surface increases, and not only the focus of the laser beam 102 is adjusted, but also the shape and contour of the beam projected on the substrate surface, The effect of size variation is becoming prominent.

  Accordingly, the laser irradiation apparatus of the present invention aims to enable the focus adjustment and the beam shape and size adjustment with high accuracy in accordance with the displacement of the substrate.

  In order to achieve the above object, a laser irradiation apparatus of the present invention includes a laser oscillator that irradiates laser light, a short-axis collimator lens that makes the laser light parallel in the short-axis direction, and a long-axis laser beam. A long-axis collimator lens that is parallel light in the direction, a condensing lens that condenses the laser light in the short-axis direction, and a long-axis direction of the laser light that is disposed between the condensing lens and the irradiation target A long-axis slit for adjusting the beam shape of the laser beam, a short-axis slit for adjusting a beam shape in the short-axis direction of the laser light, which is disposed between the condenser lens and the irradiation target, and the irradiation target of the laser light And a projection lens for irradiating the lens.

  As described above, according to the laser irradiation apparatus of the present invention, the slit is distinguished for the long axis and the short axis, and each is individually variable, so that the focus adjustment and the beam shape and size can be adjusted with high accuracy. Adjustments can be made.

The figure which illustrates a mode that a panel is irradiated with a general irradiation method Schematic diagram showing the beam shape, which is the laser irradiation area (A), (b) The conceptual diagram which shows the laser irradiation apparatus of this invention The figure explaining the shape of the long axis slit of this invention, and a short axis slit (A), (b) The figure which illustrates the structure of the variable slit of this invention (A), (b) The schematic diagram which shows the structure of the optical system in the conventional laser irradiation apparatus.

First, a general laser irradiation method will be described with reference to FIGS.
FIG. 1 is a diagram illustrating a state in which a general irradiation method is applied to a panel, and FIG. 2 is a schematic diagram showing a beam shape that is an irradiation region of a laser.

  As shown in FIGS. 1 and 2, a panel 30 which is an example of a substrate on which pixels 31 made of amorphous silicon are formed is sequentially scanned using laser light shaped into a long and narrow beam 32 having a major axis and a minor axis. . The beam 32 is shaped, for example, into a major axis direction of 1 mm and a minor axis direction of 30 μm. When the beam 32 having such a shape is scanned from the end of the panel 30 in the major axis direction and scanned to the end of the panel 30, the beam 32 moves in the minor axis direction and scans in the major axis direction again. By performing this scanning over the entire panel 30, the pixels 31 on the entire surface of the panel 30 are crystallized by laser irradiation.

Next, a laser irradiation method and an irradiation apparatus for irradiation for crystallization will be described with reference to FIGS. 3A, 3B, 4, 5A, and 5B.
3A and 3B are conceptual diagrams showing a laser irradiation apparatus of the present invention. FIG. 3A shows a beam shaping configuration in the long axis direction of the laser, and FIG. 3B shows a beam shaping configuration in the short axis direction of the laser. As shown in FIGS. 3A and 3B, the laser irradiation apparatus of the present invention shapes one laser in the major axis direction and the minor axis direction, respectively, and shapes the beam irradiation cross section into a rectangular laser. Structure.

FIG. 4 is a diagram illustrating the shapes of the long axis slit and the short axis slit of the present invention.
5A and 5B are diagrams illustrating the structure of the variable slit of the present invention. FIG. 5A shows a long axis variable slit, and FIG. 5B shows a short axis variable slit.

  In the laser irradiation apparatus of the present invention shown in FIGS. 3 (a) and 3 (b), first, the laser light 20 emitted from the laser oscillator 1 has a short-axis direction collimator lens 2 that is parallel to the short-axis direction, and a long length. The light passes through the long-axis collimator lens 3 which is parallel to the axial direction, and is shaped into laser light parallel to the long-axis direction and the short-axis direction.

  Next, the laser light 20 passes through the homogenization lens 4 made up of a pair of cylindrical lenses and is divided in the long axis direction so as to be arranged in a linear point light source and passes through the condenser lens 5. Here, the cylindrical lens is a cylindrical lens having a cross-sectional shape in the long axis direction that is a cylindrical lens shape (see FIG. 3A) and a cross-sectional shape in the short axis direction that is a flat plate shape (see FIG. 3B). . In the present embodiment, the homogenizing lens 4 uniformizes the laser power in the long axis direction, but the homogenizing lens 4 and the condenser lens 5 may be omitted depending on the characteristics of the laser light 20 and the like. Is possible.

Next, the laser light 20 that has passed through the condenser lens 5 is condensed only in the short axis direction by the short axis condensing lens 6.
Next, the condensed laser beam 20 enters the field lens 7. In a conventional optical system that does not use the field lens 7, the beam size is determined only by the long-axis slit 8 without using the field lens 7. In this case, the laser beam 20 forms an image at the slit position. However, strictly speaking, the laser beam 20 after that also includes divergent light instead of parallel light.

  The field lens 7 used in the present embodiment is a lens disposed in the vicinity of the position of the long-axis slit 8 and contributes little to the image formation of the laser light 20, but functions to change the traveling direction of the laser light 20. Yes, it works to reduce divergent light and improve directivity.

  The laser beam 20 converted into parallel rays in the long axis direction is imaged by the condenser lens 5 at the position of the long axis slit 8 provided adjacent to the field lens 7. The laser beam incident on the long-axis slit 8 is shaped into a predetermined size in the beam shape and length in the long-axis direction. By passing through the short axis slit 9 after passing through the long axis slit 8, the beam shape and length in the short axis direction are shaped to a predetermined size.

  That is, as shown in FIG. 4, the long-axis slit 8 includes a slit whose length in the long-axis direction matches the desired length in the long-axis direction of the beam. The laser beam 20 is shaped into the same shape as in FIG. The short-axis slit 9 includes a slit whose length in the short-axis direction matches the desired length of the short-axis direction of the beam, covers the entire surface of the slit, and receives laser light 20 shaped in the long-axis direction. By shaping the laser beam 20 into the same shape as the slit, the laser beam 20 is shaped into a beam shape to be irradiated onto the substrate 11 which is an example of the irradiation target together with the long-axis slit 8.

  Finally, the laser light 20 whose shape is adjusted by the long-axis slit 8 and the short-axis slit 9 is imaged on the substrate 11 by the projection lens 10. In this embodiment, a critical illumination system is formed in the short axis direction, and an image projected on the short axis slit 9 by this illumination system is projected onto the substrate 11 by an imaging optical system formed by the projection lens 10. To do.

  The feature of the present invention is that the long-axis slit 8 and the short-axis slit 9 are dividedly arranged at a position in the middle of condensing the laser beam. Further, in the present embodiment, in order to adjust the focus of the laser light 20, the projection lens 10 can be moved in a direction parallel to the irradiation direction of the laser light 20, and the long-axis slit 8 and the short-axis slit 9 are also provided. It can be moved independently.

  In the laser irradiation apparatus of the present invention, not only the projection lens 10 but also the positions of the long-axis slit 8 and the short-axis slit 9 are made variable in the laser irradiation direction, thereby responding to the displacement of the focal length due to warping or bending of the substrate 11. At the same time as the focus adjustment, the beam shape and the beam width in the major axis direction and the minor axis direction can be adjusted to predetermined values.

  That is, by adjusting the distance A from the long-axis slit 8 or the short-axis slit 9 to the projection lens 10 and the distance B from the projection lens 10 to the substrate 11 individually in the long-axis direction and the short-axis direction, high accuracy is achieved. In addition to performing focus adjustment, at least one adjustment of the shape, width, contour, etc. of the beam can be made individually.

  Further, by making the position of the short-axis direction condensing lens 6 variable, it is possible to perform focus adjustment and beam shape and width adjustment with higher accuracy, particularly in the short-axis direction. At this time, the relative position between the projection lens 10 and the substrate 11 can be measured by the displacement sensor 13 before the laser irradiation or at the time of laser irradiation, and can be adjusted according to the actual displacement amount of the substrate 11.

Hereinafter, another embodiment of the present embodiment will be described with reference to FIGS. 5 (a) and 5 (b).
As another form of the present embodiment, as shown in FIG. 5 (a), the long-axis slit 8 shown in FIGS. 3 (a) and 3 (b) can be adjusted in the width of the slit in the long-axis direction. The long axis variable slit 14 can be replaced. For example, a joint portion can be provided in the long axis variable slit 14 so that the width of the slit in the long axis direction can be expanded and contracted at the joint portion. The long axis variable slit 14 may be fixed in the laser irradiation direction. However, the long axis variable slit 14 can be moved in the laser irradiation direction like the long axis slit 8 in FIG. It is possible to cope with higher accuracy.

  Further, the short-axis slit 9 shown in FIGS. 3A and 3B is also replaced with a short-axis variable slit 15 as shown in FIG. 5B so that the width in the short-axis direction of the slit can be adjusted. You can also. This is because the slit width in the minor axis direction of the minor axis variable slit 15 is adjusted when the focal point where the laser beam 20 is condensed in the minor axis direction by the minor axis direction condenser lens 6 is deviated from the position of the minor axis slit. For example, it can be used when dealing with a focal position shift of the laser beam 20. The short axis variable slit 15 may be used together with the long axis variable slit 14 or may be used alone. The short axis variable slit 15 may also be fixed in the laser irradiation direction. However, the short axis slit 9 in FIG. 3B can be moved in the laser irradiation direction to reduce the displacement of the substrate. On the other hand, it is possible to cope with higher accuracy.

  When the distance between the long-axis slit 8 or the long-axis variable slit 14 and the projection lens 10 is A, the distance between the projection lens 10 and the substrate 11 is B, and the length between the slits is L, in the present invention, on the substrate 11 The beam size in the long axis direction is L * B / A. In the present invention, the long-axis slit 8 or the long-axis variable slit 14, the short-axis slit 9 or the short-axis variable slit 15, the projection lens 10, and in some cases, the short-axis direction condenser lens 6 are moved back and forth simultaneously during focus adjustment. , L * B / A is adjusted so as to be always constant.

  Further, for example, there is a case where the thermal lens effect due to the laser beam 20 occurs in the projection lens 10 and the lens focal point position changes (assuming that the distance A changes to the distance A ′). In this case, the slit width L ′ of the long axis variable slit 14 is changed so that the long axis direction beam size on the substrate 11 becomes L * B / A = L ′ * B / A ′, and the beam on the substrate 11 is changed. It is possible to make the width constant.

  As described above, by making it possible to move the long-axis slit and the short-axis slit in the laser irradiation direction and to expand and contract the width of the slit, the beam shape and the like can be adjusted in accordance with the displacement of the substrate.

  In the embodiments described so far, the oscillation form of the laser oscillator 1 may be a pulse wave or a continuous wave. There is also no limitation on the oscillation wavelength. Although the beam width is 1 mm in FIG. 2, it can be made as long as the power of the laser oscillator 1 permits. Conversely, the beam width may be long enough to irradiate only the transistor portion existing in one pixel.

  In the above description, the laser light generation device used for crystallization of the pixel transistor of the display device has been described as an example. However, it may be used for laser beam focus adjustment and beam shape and size adjustment used for other purposes. Is possible.

  INDUSTRIAL APPLICABILITY The present invention is useful for a laser irradiation apparatus and the like that can adjust the focus and the beam shape and size with high accuracy and can adjust the shape and size of the laser light irradiated to the irradiation target.

DESCRIPTION OF SYMBOLS 1 Laser oscillator 2 Short axis direction collimator lens 3 Long axis direction collimator lens 4 Uniform lens 5 Condenser lens 6 Short axis direction condensing lens 7 Field lens 8 Long axis slit 9 Short axis slit 10 Projection lens 11 Substrate 13 Displacement sensor 14 Long Axis variable slit 15 Short axis variable slit 20 Laser beam 30 Panel 31 Pixel 32 Beam 100 Crystallizer 101 Laser oscillator 102 Laser beam 103 Uniform lens 104 Slit 105 Projection lens 106 Thin film silicon 107 Collimator lens 108 Cylindrical lens

Claims (7)

A laser oscillator for irradiating laser light;
A short-axis collimator lens that converts the laser light into parallel light in the short-axis direction;
A long-axis collimator lens that makes the laser beam parallel light in the long-axis direction;
A condensing lens that condenses the laser light in the minor axis direction;
A long-axis slit that is arranged between the condenser lens and the irradiation target and adjusts the beam shape in the long-axis direction of the laser beam;
A short-axis slit that is arranged between the condenser lens and the irradiation target and adjusts the beam shape in the short-axis direction of the laser light;
And a projection lens that irradiates the irradiation target with the laser light. 2. The laser irradiation apparatus according to claim 1, further comprising a field lens that improves directivity of the laser light between the condenser lens and the long-axis slit and the short-axis slit. The laser irradiation apparatus according to claim 1, wherein the projection lens, the long-axis slit, and the short-axis slit are each movable in an irradiation direction of the laser light. The projection lens, the long-axis slit, and the short-axis slit are individually moved to adjust at least one of the width, contour, shape, and focus of the laser beam in the long-axis direction and the short-axis direction. The laser irradiation apparatus according to any one of claims 1 to 3. The laser irradiation apparatus according to claim 1, wherein a slit width in a major axis direction of the major axis slit is variable. The laser irradiation apparatus according to claim 1, wherein a slit width in a short axis direction of the short axis slit is variable. The said irradiation object is a display apparatus, The amorphous silicon film formed in the said display apparatus is crystallized to a polysilicon film by irradiation of the said laser beam, The one in any one of Claims 1-6 characterized by the above-mentioned. Laser irradiation device.

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