JP2008153448A - Laser drawing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laser drawing apparatus wherein it is so constituted that even a largely deflected laser light is always made incident on the pupil center of its objective lens, and its image-plane curvature and its miscellaneous aberrations can be reduced, and further, its structural space can be reduced. <P>SOLUTION: The laser drawing apparatus has a laser light source 4, a scanning portion 5 for deflecting a laser light 6 made outgoing from the laser light source 4, and opposite first and second fθ lens groups to each other 2, 3 for making the deflected laser light 6 incident on an objective lens 7. The first ad second fθ lens groups are so constituted that their exit pupils are infinite and that they are telecentric optical systems and that the laser light 6 is always made incident on the pupil center of the objective lens 7. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a laser drawing apparatus having an optical system using an fθ lens.

In recent years, a thin film transistor (TFT) is used as a switching element in, for example, a liquid crystal display and other flat display devices. In manufacturing a thin film transistor or the like, laser annealing is performed by irradiating a laser beam to crystallize an amorphous semiconductor thin film formed on a substrate.
As a laser processing apparatus that can be suitably used for annealing a semiconductor thin film in which a thermal load on a substrate such as a TFT is kept small, there is a processing apparatus that irradiates a substrate with laser light at high speed (Patent Document 1). FIG. 5 shows a schematic configuration of a main part of the laser processing apparatus. According to this, in the laser processing apparatus 50, the laser beam Lh emitted from the light source unit 53 passes through the plurality of collimating lenses 55a and 55a and the anamorphic prism 55b in the beam shaping unit 55, and thereby has a beam diameter. It is shaped. Then, the laser beam Lh whose beam diameter has been shaped enters the scanning unit 57 that can be scanned in a predetermined direction via the two mirrors 65a and 65b, and the laser beam Lh is the substrate W that is the object to be processed. Is irradiated. The laser beam Lh scanning unit 57 includes a galvano-mirror system that is reciprocally rotated, and an AOD (Acousto-Optic-Device) that modulates and deflects light by the interaction between sound waves and light waves in the material. A system, MEMS (Micro Electro Mechanical System) is used.

By the way, in such laser annealing, a laser beam scan angle is required to some extent, and the laser beam is largely deflected by an AOD or the like which is a laser beam scanning unit. However, when laser light largely deflected by AOD or the like is incident on the objective lens, there is a problem that a deviation between the principal ray of the deflected laser light and the entrance pupil of the objective lens becomes large. As a result, the deflected laser beam is kicked by the pupil of the objective lens, causing a great decrease in the amount of light. Further, when the laser beam passes through the edge of the objective lens, there is a possibility that spherical aberration and field curvature increase.
In Patent Document 1, an fθ lens 63 is provided between a substrate W, which is an object to be processed, and a scanning unit 57 such as an AOD, and laser light Lh is condensed by a condenser lens (not shown) and irradiated onto the substrate W. A laser processing apparatus is disclosed.
JP 2006-134986 A

However, in the configuration of the optical system as described above, there may be no space for arranging the fθ lens around the objective lens. Then, the fθ lens having a large focal length is disposed away from the objective lens, but in this case, the entire optical system becomes large. Further, in the configuration having a pair of fθ lenses as in Patent Document 1, when the scan angle is increased, the laser light is kicked to the entrance pupil of the condenser lens, and the amount of light is reduced.
Further, when the laser to be used is a semiconductor laser, there is a problem that chromatic aberration is likely to occur because the wavelength width is wider than that of a gas laser.

  In view of the above-mentioned points, the present invention is configured so that even a largely deflected laser beam is always incident on the pupil center of the objective lens, and field curvature and various aberrations can be reduced. It is an object of the present invention to provide a laser drawing apparatus that can be made simple.

  In order to solve the above problems and achieve the object of the present invention, a laser drawing apparatus of the present invention comprises a laser light source, a scanning unit for deflecting laser light emitted from the laser light source, and a deflected laser light. The first fθ lens group and the second fθ lens group that face each other for entering the objective lens, and the first and second fθ lens groups have an exit pupil at infinity and are telecentric optics By forming a system, the laser light is always incident on the center of the pupil of the objective lens.

  In the laser drawing apparatus of the present invention, the first fθ lens group and the second fθ lens group form a telecentric optical system so that the laser light deflected by the scanning unit is incident on the entrance pupil of the objective lens. become.

  According to the present invention, since the deflected laser light is always incident on the pupil center of the objective lens, it is possible to suppress a decrease in the light amount of the laser light incident on the objective lens. Furthermore, since the first fθ lens group and the second fθ lens group form a telecentric optical system, lens replacement is facilitated.

  The laser drawing apparatus according to the present invention has a first fθ lens group and a second fθ lens group that face each other, and is a telecentric optical system, whereby these first fθ lens group and second fθ lens group are formed. Laser light that is incident on the objective lens via the lens group is always incident on the center of the pupil of the objective lens.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 shows a schematic configuration diagram of a laser drawing apparatus according to the first embodiment of the present invention. In the present embodiment, the laser drawing apparatus 1 is mainly used for laser annealing in a semiconductor manufacturing process.

  First, the laser drawing apparatus 1 in the present embodiment is deflected by a laser light source 4 serving as an exposure light source, a scanning unit 5 for deflecting the laser light 6 emitted from the laser light source 4, and the scanning unit 5. First and second fθ lens groups 2 and 3 for making the laser beam 6 enter the center of the entrance pupil of the objective lens 7 and a dichroic mirror 8 for reflecting the laser beam 6 incident on the objective lens 7 are provided. . In the optical system of the laser drawing apparatus 1 of the present example, the first fθ lens group 2 has a two-group configuration, and the second fθ lens group 3 has a four-group configuration. Furthermore, the laser drawing apparatus 1 according to the present embodiment includes a focus control unit 9 so as to have a focus servo function with respect to the surface of the substrate 10 that is the object to be processed. The objective lens 7 is located in front of the substrate 10. The laser beam scanning unit 5 includes a galvano-mirror system that reciprocally rotates, and an AOD (Acousto-Optic-Device) system that modulates and deflects light by the interaction of sound waves and light waves in the material. MEMS (Micro Electro Mechanical System) is used.

  In the laser drawing apparatus 1 of this example, the deflected laser light 6 enters the objective lens 7 through the first and second fθ lens groups 2 and 3 facing each other. The fθ lens is a lens that can change the position of a focused spot in proportion to the angle of incident deflected laser light, and has a constant velocity spot scanning property proportional to the deflection angle θ of the laser light. It is the lens comprised as follows. In the first fθ lens group 2, assuming that the focal length is f and the incident angle of the laser beam is θ, the laser beam incident at the angle θ is condensed from the optical axis 16 at y = fθ.

  The first fθ lens group 2 includes a group of lenses, that is, a lens portion group 11. The lens portion group 11 is formed by bonding two lenses 11a and 11b having different refractive indexes and dispersion. Achromatic correction has been made. The first fθ lens group has a so-called two elements in one group. Next, when viewed from the first fθ lens group 2, the second fθ lens group 3 is arranged in a three-group configuration including three groups of lenses, that is, lens portion groups 12, 13 and 14, and the lens portion group Achromatic correction 14 is performed by attaching two lenses 14a and 14b having different refractive indices and dispersion. This second fθ lens group 3 is constituted. In addition, the surface powers of the lens portion groups 12, 13, and 14 are in the order of positive, negative, and positive (so-called convex, concave, convex). Further, apochromatic correction is performed by the lens portion groups 12, 13, and 14.

At this time, in order to facilitate lens replacement when changing the effective numerical aperture (NA) of the objective lens 7, the exit pupils of the first, second, and both fθ lens groups 2 and 3 are set to infinity. In other words, the lens groups are arranged facing each other in a telecentric manner. When the optical system is not a telecentric system, each principal ray of the deflected laser light is not parallel to the central axis (optical axis) of the lens, so when changing one lens to another lens, there are various new Adjustments must be made and lens replacement is not easy.
By making the first and second fθ lens groups 2 and 3 face each other in the telecentric system, the principal ray 17 of the deflected laser beam 6 becomes parallel to the central axis (optical axis 16) of the lens. Lens replacement is easy. Further, even when the laser beam 6 is deflected, the spot is narrowed in parallel with the optical axis 16, so that the loss of light quantity is small.

  The first and second fθ lens groups 2 and 3 are arranged such that the rear focal point 19 in the first fθ lens group 2 and the rear focal point 20 in the second fθ lens group 3 coincide. Yes. In the configuration of this example, the second fθ lens group 3 side is the rear side for the first fθ lens group 2, and the first fθ lens group 2 side is the rear side for the second fθ lens group 3. It is.

As shown in FIG. 1, in this example, the laser light 6 emitted through the first fθ lens group 2 is focused on the rear focal point 19 and then the focus of the first fθ lens group 2. Each laser beam 6 having 19 as a light source enters the second fθ lens group 3. At this time, the laser beam 6 is telecentric between the first fθ lens group 2 and the second fθ lens group 3, and the principal ray 17 is parallel to the optical axis 16. Further, the laser light 6 is finely adjusted and emitted by the three lenses of the second fθ lens group 3. Thereafter, the laser beam 6 is reflected by the dichroic mirror 8 and enters the objective lens 7.
At this time, in the second fθ lens group 3, the laser light 6 is adjusted by the lens portion groups 12, 13, and 14, so that it enters the center of the pupil of the objective lens 7. The laser beam 6 emitted from the objective lens 7 forms a spot on the substrate 10 and laser annealing is performed. In other words, the laser beam 6 is deflected by the scanning unit 5 to be scanned by the substrate 10, and a predetermined region can be selectively laser-annealed. By moving the substrate 10 relative to the laser drawing apparatus 1, it is possible to anneal the entire area of the substrate 10 or a necessary area.

  At this time, the focus control unit 9 emits focus laser light (hereinafter referred to as focus light) 18 from the focus light source 15 and is guided onto the substrate 10 through the dichroic mirror 8 along the same optical path as the laser light 6. The focus light 18 is reflected on the substrate 10, and the focus servo 18 is enabled by the focus light 18 that is reflected and returned. As a result, the laser beam 6 is always irradiated with the focal point being the surface of the substrate 10. The dichroic mirror 8 can be configured to reflect, for example, laser light 6 with blue wavelength light (for example, 405 nm) and transmit focus light 18 with red wavelength light (for example, 650 nm).

According to the laser drawing apparatus 1 described above, the second fθ lens group 3 has a triplet configuration including four lenses in three groups, and by using an appropriate lens for each, the laser beam 6 greatly deflected can be converted into the fθ lens. Even when passing through the edge portion, an increase in spherical aberration and curvature of field can be suppressed.
Further, each of the first fθ lens group 2 and the second fθ lens group 3 is configured such that achromatic correction and apochromatic correction are performed by bonding lenses having different refractive indexes and dispersions. Achromatic correction and apochromatic correction reduce chromatic aberration.

  In addition, since the second fθ lens group 3 has a triplet configuration including at least three lens groups, the refraction of the laser light 6 can be adjusted, so that an increase in various aberrations can be suppressed. The focal length of the second fθ lens group 3 can be reduced, and the total length of the optical system in the laser drawing apparatus 1 can be reduced. Further, since the rear focal point 19 of the first fθ lens group 2 and the rear focal point 20 of the second fθ lens group 3 coincide with each other and form a telecentric optical system, the first fθ lens. Even when the group 2 is replaced with one having a large focal length, the second fθ lens group 3 can be used as it is, and the lens can be easily replaced.

  Hereinafter, the relationship between the optical path of the laser beam and the focal length will be described using the second and third embodiments of the present invention with reference to schematic views.

  2A and 2B schematically show a laser drawing apparatus according to the second embodiment of the present invention. However, the same parts as those in the first embodiment are denoted by the same reference numerals, and the overlapping description is omitted.

  The laser drawing apparatus 40 of the present example includes a light source 4 of laser light 6 and a scanning unit 5 for deflecting a scan angle of the laser light 6, a first fθ lens group 2, a second fθ lens group 33, and an objective lens. 7 Other components are omitted. In the present embodiment, the first and second fθ lens groups 2 and 33 are arranged with the same fθ lens facing each other. In other words, in this example, the lens portion groups (not shown) of the first and second fθ lens groups 2 and 33 are both configured in one group, and the first and second fθ lens groups 2 and 33 are configured. The rear focal points are arranged so as to coincide with each other, and the exit pupils of the respective fθ lens groups 2 and 33 are infinite. Thus, by making the first and second fθ lens groups 2 and 33 having the same specifications face each other and forming a telecentric optical system, the beam of the laser beam 6 emitted from the light source 4 and deflected by the scanning unit 5 is used. Is incident on the center of the entrance pupil of the objective lens 7 through the first and second fθ lens groups 2 and 33 facing each other. According to this configuration, even when the scanning angle is greatly deflected by the scanning unit 5, the loss of light quantity is reduced without being kicked by the pupil of the objective lens 7.

  In the present embodiment, the first and second lens groups 2 and 33 facing each other have the same configuration, and the focal lengths f0 of both lens groups are equal. Therefore, as shown in FIG. When the lens is replaced with a lens having a large focal length, the other lens may be replaced with a lens having the same focal length. That is, as in the laser drawing device 41 shown in FIG. 2B, when the focal length of one lens group is f00, the focal length of the other lens group is also f00, so that the laser light 6 is emitted from the objective lens 7. It is not kicked by the eyes.

  3A and 3B are schematic views of a laser drawing apparatus according to the third embodiment. In the laser drawing apparatuses 42 and 43 of this example, the second fθ lens group 3 has a configuration of four elements in three groups. The first fθ lens group 2 has a two-group configuration, and the second fθ lens group 3 has a four-group configuration. Here, like the first embodiment, it is schematically illustrated. Since the other components except the second fθ lens group 3 are the same as those in the first embodiment, the same reference numerals are given and the overlapping description is omitted.

  In the second embodiment described above, the beams are made incident without being kicked by the entrance pupil of the objective lens 7 by making the focal lengths of the first and second fθ lens groups 2 and 33 equal. However, as shown in FIG. 3, the second fθ lens group 3 is composed of three groups of lenses having a combination of positive, negative, and positive surface powers, so that the focal length f1 of the first fθ lens group 2 is increased. The beam can be incident on the pupil of the objective lens without being affected. That is, f1 = f2 may not be satisfied. For example, as shown in FIG. 3B, when the first fθ lens group 2 is replaced with one having a focal length of f3, the second fθ lens group 3 may be left as it is, and the first fθ lens group 2 There is no need to match the focal length f3. That is, even if the focal length f3 increases, the entire optical system does not increase.

Therefore, according to the laser drawing apparatuses 42 and 43 of this example, an increase in the optical system space resulting from the replacement of the second fθ lens group 3 can be prevented, and space saving can be achieved. However, it is necessary to change the optical path length so that the rear focal point of the first fθ lens 2 and the rear focal point of the second fθ lens 3 coincide.
Furthermore, since the second fθ lens group 3 can be shortened in focal length by the lens configuration of four elements in the third group, the entire optical system can be shortened.

  In the laser drawing apparatus 42 of FIG. 3A, the beam diameter of the laser light 6 oscillated by the light source 4 and incident on the scanning unit 5 is φ1, and the beam diameter incident on the objective lens 7 is φ2. Then, the relationship of φ2 = (f2 / f1) · φ1 is established in the beam diameter. Similarly, in FIG. 3B, the focal length of the first fθ lens group is f3, the beam diameter of the laser beam 6 incident on the scanning unit 5 is φ1, and the beam diameter of the laser beam 6 incident on the objective lens 7 is φ3. Then, φ3 = (f2 / f3) · φ1. If there is a relationship of f3> f1 in the focal length, a relationship of φ3 <φ2 is established. That is, when the first fθ lens group 2 is replaced with one having a large focal length, it can be seen that the beam diameter φ3 of the laser light 6 incident on the objective lens 7 becomes small.

Accordingly, since the first fθ lens group 2 can be easily replaced with a lens group having a different focal length, the beam diameter incident on the objective lens 7 can be easily changed.
In addition, the angle of the laser beam incident on the substrate can be changed by replacing the first fθ lens with a lens having a different focal length.

  Next, a specific configuration will be described in detail as a fourth embodiment according to the present invention. In the second embodiment, specific means and numerical values are applied to the laser drawing apparatus 1 in the first embodiment. Therefore, the same reference numerals are given to the same parts, and overlapping explanation is omitted.

  FIG. 4 shows a schematic configuration diagram of a laser drawing apparatus according to the second embodiment of the present invention. In the laser drawing apparatus 30 in the present embodiment, a semiconductor laser 31 is used as a laser light source that is an exposure light source, and an AOD (acousto-optic element) 32 is used as a scanning unit for deflecting the laser beam. The AOD 32 is an element that diffracts incident light by forming a diffraction grating by causing an ultrasonic wave to propagate through a crystal by a vibrator driven by a high-frequency signal to cause a periodic refractive index change. That is, by changing the frequency of the diffraction control signal input to the AOD 32, the emission direction of the laser light 6 incident on the AOD 32 and diffracted is changed. That is, the laser beam 6 can be deflected.

  First, the semiconductor laser 31 having a wavelength of 450 nm is collimated to form an exposure light source. The laser beam 6 is incident on the AOD 32 with a beam diameter of φ = 1.5 mm, and first-order diffracted light is used as an exposure beam. This first-order diffracted light is incident on the first fθ lens group 2. Here, the first fθ lens group 2 includes a lens portion group 11 having two lenses in one group, and is designed so that the focal length is about 140 mm and the exit pupil is negative infinity. Furthermore, achromatic correction is also performed. The surface data of the first fθ lens group 2 having two lenses in one group is shown below. However, the surfaces of the first fθ lens group 2 are S1, S2, and S3 from the incident side of the laser beam 6, and the curvature radii of the surfaces are R1, R2, and R3, respectively. The glass material between the surfaces S1 and S2 and the thickness on the optical axis are G1, and the glass material between the surfaces S2 and S3 and the thickness on the optical axis are G2.

S1: R1 = 170.874 mm
S2: R2 = 44.171 mm
S3: R3 = −121.450 mm
G1: S-TIM2 (Ohara) /2.0mm
G2: S-BAL14 (Ohara) /2.0mm
In the curvature radius R, a negative sign means a convex surface when viewed from the light source 4 side (left side), and a positive sign means that it is a concave surface when viewed from the light source 4 side (left side). The glass materials of G1 and G2 are glass materials manufactured by OHARA.

At this time, even if the beam is deflected from the optical axis 16 that is the central axis of the optical system by matching the fulcrum B of scanning by the AOD 32, that is, the so-called scanning fulcrum B, with the front focal point of the first fθ lens group 2. The principal ray 17 emitted from the fθ lens group 2 is parallel to the central axis (optical axis 16) of the optical system.
Further, since the achromatic correction is performed, the height of the optical axis of the outgoing beam from the fθ lens group is constant even when the laser beam 6 having the wavelength width by the semiconductor laser 31 is used. Incidentally, even if the designed wavefront aberration by the first fθ lens group is deflected ± 1 degree with respect to the laser beam 6 having the beam diameter φ = 1.5 mm, it becomes ± 1 mλ or less. Further, at the time of maximum deflection of the laser beam 6, the emission angle of the emission principal ray 17 with respect to the optical axis 16 is 5 μrad or less.

Next, the condensing position A of the laser beam 6 by the first fθ lens group 2 is regarded as a new emission point, and the laser beam 6 is incident on the second fθ lens group 3 from the opposite side. The second fθ lens group 3 has a triplet configuration including four lens portion groups 12, 13, and 14 that are designed to have a focal length of about 400 mm and an entrance pupil at negative infinity. In the lens portion groups 12, 13 and 14, apochromatic correction is performed. Here, the surface data of the second fθ lens group 3 is shown below.
However, the surfaces of the second fθ lens group 3 are S4, S5, S6, S7, S8, S9, S10 from the objective lens 7 side, and the curvature radii of the respective surfaces are R4, R5, R6, R7, Let R8, R9, R10. Further, the glass material between the surfaces S4-S5 and the thickness on the optical axis 16 is G3, the glass material between the surfaces S5-S6 and the thickness on the optical axis 16 is G4, the distance on the optical axis 16 between the surfaces S5-S6 is G5, and the surface S6. The thickness of the glass material between S7 and the optical axis 16 is G6, the distance on the optical axis 16 between the surfaces S7 and S8 is G7, and the thickness of the glass material between the surfaces S8 and S9 and the thickness on the optical axis 16 is G8.

S4: R4 = 145.965 mm
S5: R5 = 72.952 mm
S6: R6 = Infinity
S7: R7 = Infinity
S8: R8 = 46.000 mm
S9: R9 = 93.946 mm
S10: R10 = −183.325 mm
G3: S-TIM2 (Ohara) /1.0 mm
G4: S-BAL14 (Ohara) /2.0 mm
G5: 221.2 mm
G6: SiO2 / 2.0 mm
G7: 46.4 mm
G8: SiO2 / 2.0mm
As described above, in the radius of curvature R, a negative sign is a concave surface when viewed from the objective lens 7 side (right side), and a positive sign is a convex surface when viewed from the objective lens 7 side (right side). The glass materials of G3 and G4 are glass materials manufactured by OHARA.

  The rear focal position of the second fθ lens group 3 is arranged so as to coincide with the beam emission point A. At this time, the first fθ lens group 2 and the second fθ lens group 3 which are designed so that the exit pupils are at negative infinity are opposed to each other so that their rear focal positions coincide. ing. In this optical system configuration, the laser beam 6 scanned at any deflection angle becomes a parallel beam toward the entrance pupil center of the objective lens 7. That is, the first fθ lens group 2 and the second fθ lens group 3 are opposed to each other so that the back focal point positions coincide with each other, the front focal point of the first fθ lens group 2 coincides with the diffraction position of the AOD 32, Further, by making the front focal point of the second fθ lens group 3 coincide with the entrance pupil position of the objective lens 7, it functions as a low aberration afocal relay optical system. Further, the beam diameter is enlarged by the focal length ratio of both lens groups, that is, 400/140, and at the same time the deflection angle is reduced to its reciprocal 140/400 = 0.35 times.

  Further, the design wavefront aberration due to the second fθ lens group 3 described above is ± 1 mλ or less even when deflected by ± 4 degrees with respect to a beam having a beam diameter φ = 3.8 mm. At the time of maximum deflection of the beam, the exit angle of the exit principal ray 17 with respect to the optical axis 16 is 5 μrad or less.

  As described above, in the laser drawing apparatus 30 according to the present embodiment, by using the lens configuration described above, the diffracted light of the laser light 6 changed by the AOD 32 can be reliably transmitted to the objective lens 7 regardless of the deflection angle. At the same time, it is possible to suppress an increase in various aberrations including curvature of field and spherical aberration that occur at the imaging position due to scanning. Further, chromatic aberration can also be suppressed by achromatic correction and apochromatic correction.

  In this example, the amount of chromatic aberration subjected to achromatic correction is Δf = 5.4 μm / nm in the first fθ lens group (focal length is about 140 mm), and the second fθ lens group (focal length is about 400 mm). Δf = 2.2 μm / nm. Since the amount of chromatic aberration due to the plano-convex quartz single lens (center thickness is 2 mm, focal length is about 400 mm) is Δf = 88.0 μm / nm, it can be said that the chromatic aberration is sufficiently suppressed by the achromatic correction of this example.

  Here, when the effective NA is lowered in order to change the exposure condition, the first fθ lens group 2 is changed to another fθ lens group having only the focal length of 175 mm, for example, by an equivalent design, thereby moving to the objective lens 7. The incident beam diameter can be reduced to 80%. As a result, the effective NA becomes relatively small, and the focused spot diameter can be increased. At the same time, as compared with the case where the first fθ lens group 2 having a focal length of 140 mm is used, the incident angle to the objective lens 7 is 1.25 times, and the scan area on the condensing surface of the objective lens 7 is also 1 .25 times.

  As described above, in the laser drawing device 30, when the first fθ lens group 2 is changed to another fθ lens group having a different focal length by using the configuration of the lens group described above, the optical path length is changed. Although adjustment is required, the other second fθ lens group 3 can be used as it is. Since the second fθ lens group 3 is composed of the lens group groups 12, 13, and 14 of the three groups, the length of the optical system can be shortened, so that the second fθ lens group 3 is used as it is. This can lead to space saving of the device. This also makes it easy to change the optical conditions. Moreover, the magnification of the angle of the laser beam 6 incident on the objective lens 7 can be changed by changing the focal length of one fθ lens group.

  Further, when the laser beam emitted from the light source is deflected by AOD or the like when the beam diameter is large, the response speed becomes slow. Therefore, it is preferable that the beam diameter of the laser light emitted from the light source is small. However, in laser annealing or the like, there are cases in which it is desired to increase the beam diameter of the laser light focused on the substrate. According to the laser drawing apparatus 30 of this example, the laser beam 6 emitted from the semiconductor laser 31 with a small beam diameter is changed to the substrate through the objective lens 7 by changing the focal length of only the first fθ lens group 2. The beam diameter of the laser beam 6 formed on 10 can be enlarged.

  By using the laser drawing apparatus of the present invention, a TFT can be formed and a highly reliable liquid crystal display can be formed.

1 is a schematic configuration diagram of a laser drawing apparatus according to a first embodiment of the present invention. 1A and 1B are schematic diagrams of a laser drawing apparatus in Embodiment 1 of the present invention. A, B It is a schematic diagram of the laser drawing apparatus in Example 2 of this invention. It is a schematic block diagram of the laser drawing apparatus which concerns on 2nd Embodiment of this invention. It is a schematic block diagram of the conventional laser processing apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 30, 40, 41, 42, 43 ... Laser drawing apparatus, 2 ... 1st f (theta) lens group, 3, 33 ... 2nd f (theta) lens group, 4 ... Laser light source, 5 ... Scanning part, 6 ... Laser beam, 7 ... Objective lens, 8 ... Dichroic mirror, 9 ... Focus control part, 10 ... Substrate, 11, 12, 13, 14, ... Lens portion group, 15: focus light transmission unit, 16: optical axis, 17: chief ray, 18: focus light, 19, 20: rear focal point, 31: semiconductor Laser, 32 ... AOD, 53 ... Light source, 55 ... Beam shaping, 65a, 65b ... Mirror, 57 ... Scanning unit, 63 ... fθ lens

Claims (7)

A laser light source;
A scanning unit for deflecting the laser light emitted from the laser light source;
A first fθ lens group and a second fθ lens group facing each other for allowing the deflected laser light to enter the objective lens;
The first and second fθ lens groups are configured such that the laser beam is always incident on the pupil center of the objective lens by forming a telecentric optical system with an exit pupil at infinity. Laser drawing device. Of the first and second fθ lens groups facing each other, the second fθ lens group on the objective lens side includes at least three groups of lenses whose surface powers are positive, negative, and positive. The laser drawing apparatus according to claim 1, wherein: The laser drawing apparatus according to claim 1, wherein the first and second fθ lens groups are subjected to achromatic correction and apochromatic correction, respectively. The laser drawing apparatus according to claim 2, wherein the first and second fθ lens groups are subjected to achromatic correction and apochromatic correction, respectively. The laser light source comprises a semiconductor laser,
The laser drawing apparatus according to claim 1, wherein the scanning unit includes an AOD (acousto-optic element). The laser light source comprises a semiconductor laser,
The laser drawing apparatus according to claim 2, wherein the scanning unit includes an AOD (acousto-optic element). It has a focus control unit and a dichroic mirror for focusing the workpiece,
The dichroic mirror is disposed on an optical path between the objective lens and a second fθ lens on the objective lens side,
The laser drawing apparatus according to claim 1, wherein the focus laser beam from the focus control unit is incident on the objective lens via a dichroic mirror.

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