JP2010044272A - Laser radiation device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laser beam projection device capable of projecting a laser beam having a sufficient light amount for an object to be processed and having an arbitrary cross-sectional shape without being restricted by the wavelength of the laser beam used. <P>SOLUTION: Output light from a laser light source (1) is radiated on a mirror array of a DMD (2), and its reflected diffraction light is focused on the object to be processed (8) by a condensing lens (3) and an objective lens (4). The DMD (2) is inclined at an appropriate angle (β) so that the light that has passed through the mirror array is not split into two. Thereby, the light that has passed through the mirror array can be transmitted to the object to be processed efficiently without being split into two. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a laser irradiation apparatus suitable for various types of processing using laser irradiation (for example, heating, melting, vaporization, cutting, exposure recording, CVD (Chemical Vapor Deposition), etc.), and in particular, a digital micromirror, The present invention relates to a laser irradiation apparatus that uses a device (hereinafter referred to as “DMD”) to irradiate light from a laser light source in a desired cross-sectional shape on an object.

  2. Description of the Related Art Conventionally, a laser irradiation apparatus that can irradiate light from a laser light source into a desired cross-sectional shape on a target by using a DMD is known (see, for example, Patent Document 1).

  A typical example of the laser irradiation apparatus described in the document 1 is shown in FIG. As shown in the figure, this laser irradiation device (referred to as “laser processing device” in the same document) includes a laser light source 101 that emits a laser beam and a sample table on which a sample to be processed is placed. 108, a DMD 103 that is directly above the sample table 108 and is arranged in a substantially horizontal posture with its reference plane (defined by the reflecting surfaces of a series of micromirrors in the initial posture) facing downward, It has the 1st image pick-up element 110 for monitoring a laser irradiation state, and the 2nd image pick-up element 114 for monitoring an irradiation laser beam.

  As is well known to those skilled in the art, a mirror array comprising a number of micromirrors arranged vertically and horizontally is provided on the substrate of the DMD 103, and each of the micromirrors constituting this mirror array is It is possible to selectively take at least an initial posture and one or more tilt postures by an electrical signal given from the outside.

  For example, in the case of the DMD 103 shown in the figure, 800 × 600 tiltable micromirrors having a size of 10 μm square and a highly efficient reflecting surface formed by depositing a metal film on the surface are arranged in an array. They are arranged so that each can be tilted at an inclination angle of ± 12 degrees with respect to a reference plane (defined by a reflecting surface of a series of micromirrors in an initial posture).

  Between the laser light source 101 and the DMD 103, an illumination optical system 102 for processing the light from the laser light source 101 to obtain a laser beam B1 for illumination is interposed. The illumination optical system 102 is an optical system that converts a laser beam emitted from the laser light source 101 into a substantially parallel light beam with a uniform cross-sectional intensity distribution. For example, a fly-eye lens, a diffraction element, an aspheric lens, and a kaleido rod are used. Various configurations such as those used are known.

  Between the DMD 103 and the sample table 108, a coaxial incident type projection optical system including a condenser lens 104, an objective lens 105, and a half mirror 106 is provided. This projection optical system uses only the laser beam B11 that is generated by being reflected by the tilted micromirror among the laser beam B1 coming from the illumination optical system 102, and the condensing lens 104, the half mirror 106, and the objective lens. It is configured to lead to a sample (not shown) on the sample table 108 via 105. Reference numeral 107 denotes an illuminator for sample illumination.

  Light from a sample (not shown) on the sample table 108 travels back through the objective lens 105 to reach the half mirror 106, where the direction is changed at a right angle, and then the first imaging is performed via the imaging optical system 109. The light enters the element 110 and is converted into a video signal. The video signal is subjected to predetermined image processing in the first image processing unit 111, whereby the first control signal to be used for the micromirror tilt control of the DMD 103 and the first control signal to be supplied to the controller 116. 2 control signals.

  The controller 116 controls the XY position of the DMD 103 in the horizontal plane by driving the biaxial displacement actuator 118 via the actuator driver 117 while confirming the current position based on the second control signal.

  Between the DMD 103 and the second image sensor 114, only the laser beam B 12 that is generated by being reflected by the micromirror in an inclined posture among the laser beams B 1 coming from the illumination optical system 102 is sent to the second image sensor 114. Relay optical system 112 and attenuation filter 113 are provided.

  The laser beam B12 incident on the second image sensor 114 is converted into a video signal here. This video signal is sent to the second image processing unit 115 and converted into a third control signal to be provided to the control device. Based on the third control signal, the controller 116 diagnoses the deterioration of the individual micromirrors constituting the mirror array of the DMD 103. The driving mode of the laser light source 101 is controlled according to the diagnosis result.

  As described above, in the laser irradiation apparatus (laser processing apparatus) described above, only the tiltable micromirrors arranged on the mirror array of the DMD 103 are tilted and the lasers coming from the light source. An arrangement pattern of a group of micromirrors in a first tilt posture with a laser beam coming from the light source by accurately directing the beam in the direction of the optical axis of the condenser lens 104 constituting the projection optical system The sample is shaped into a cross-sectional shape corresponding to the above, and the sample can be irradiated.

  It should be noted that the beam cross-sectional shape control by DMD mirror tilt control described above is expected to be applied to a conventional laser CVD apparatus as shown in FIG. That is, in the figure, 201 is a laser light source, 202 is an attenuator for attenuating light emitted from the laser light source 201, and 203 is an illumination optical system for converting the attenuated light into illumination light having a uniform cross-sectional intensity. , 204 is a slit for shaping the cross-sectional shape of the illumination light, 205 is a condensing lens, 206 is an objective lens, 207 is a gas supply device for supplying a gas containing a target metal to be processed to a processing target site, Reference numeral 208 denotes a workpiece, and 209 denotes a moving stage on which the workpiece is placed.

In the apparatus shown in FIG. 13, if the beam cross-sectional shape control based on the above-described DMD mirror tilt control is adopted instead of the laser light source 201, the desired cross-sectional shape of the light from the laser light source is applied to the workpiece 208. Compared with the conventional example in which laser beam drawing is performed on the workpiece 208 while interlocking the opening / closing of the slit 204 and the movement of the moving stage 209, the configuration of the apparatus is simplified. In addition, the drawing accuracy and drawing speed can be improved.
JP 2006-227198 A

  By the way, since the DMD 103 is a system in which a large number of tiltable micromirrors are regularly arranged on a reference plane, the DMD 103 has a property as a mere assembly of micromirrors and a property as a diffraction grating in which a large number of micromirrors are assembled. And both.

  The property as a mere micromirror assembly is manifested as a phenomenon in which the power is deflected in the direction in which the incident angle and the outgoing angle of the laser beam are approximately equal on the reflecting surface of each micromirror.

  On the other hand, the properties of a diffraction grating made up of a large number of micromirrors are that the wavenumber vector of incident light and the periodicity of a series of micromirrors are related to the in-plane direction component of the reference plane where the micromirrors are arranged Appears as a phenomenon in which the sum of and becomes equal to the wave number vector of the emitted light.

In other words, when expressed in mathematical formulas:

Λsin (2α) = mλ

v = w = 13.68 μm

Λ ² = v ² + w ²

This relationship holds. Here, Λ is the arrangement pitch of the micromirrors, 2α is the incident angle with respect to the reference plane on which the micromirrors are arranged, m is an arbitrary integer, and λ is the wavelength of the laser light emitted from the laser light source 101.

  Since the mirror array has the property of a diffraction grating made up of a large number of micromirrors, the light reflected by each micromirror of the mirror array is not emitted only in one specific direction, but is diffracted. The light is emitted at a series of angles with a dispersion tendency corresponding to the value of the order m.

Here, the diffraction order m is

Λ {sin (2α + β) −sinβ} = mλ

When the wavelength λ of the laser beam is selected so that the value of the diffraction order m is an integer, the intensity of the reflected light is divided into several discrete emission angles separated from each other by the same angle. concentrate. Here, v and w are the vertical pitch and the horizontal pitch of the movable mirror surface (see FIG. 2 described later).

  Therefore, in the conventional DMD product, in order to improve the light transmission efficiency between the incident light and the emitted light, the wavelength λ of the laser beam used is recommended for each DMD product. Is decided. For example, in the case of one DMD product of Texas Instruments Inc., the value of each parameter is determined so that the use wavelength λ is a recommended value of 550 nm.

  On the other hand, the wavelength of the laser used in this type of laser irradiation apparatus is selected to have the best processing efficiency in consideration of the material of the processed portion of the workpiece. For example, when processing a photoresist film coated on a glass substrate, a YAG laser (wavelength λ1 = 1.004 μm) having a pulse width of about several nanoseconds and a peak output of about several megawatts (MW), Third and fourth harmonics (wavelengths λ2 = 532 nm, λ3 = 355 nm, and λ4 = 266 nm, respectively) are preferable as the laser light source.

However, when the above-mentioned Texas Instruments DMD is used as a DMD product and the third harmonic of a YAG laser (λ3 = 355 nm) preferable for processing is used as the laser light source 101, the diffraction order m is

α = 12 °

λ = 0.355μm

Ｍ m = 22.2

And not an integer.

  In this case, two diffracted rays are emitted from the DMD by exciting the 22nd order mode and the 23rd order mode, but 2α of the 22nd order diffracted ray is 23.8 degrees, The 23rd-order diffracted light beam 2α is 25.0 degrees, and these diffracted light beams form an angle of 1.2 degrees with each other. Therefore, the converging lens 104 with a focal length of 200 mm and the objective lens 105 with a focal length of 4 mm. Are taken as an example of a projection optical system arranged so that the distance between them is 200 mm, the diffracted light beams are condensed at an interval of 4.2 mm by the objective lens 105.

  Therefore, for example, when an objective lens 105 having a numerical aperture of 0.42, that is, a pupil diameter of 3.4 mm (= 4 mm × 0.42 × 2) is selected, two diffracted rays are simultaneously reflected in the pupil. Therefore, a considerable amount of light is kicked by the pupil, and there is a problem that laser projection with a sufficient amount of light cannot be performed unless the light amount of the light source is increased excessively.

  In addition, in the conventional laser irradiation apparatus using DMD, as described below, there are problems in light control technology, problems in film thickness control when applied to CVD, as described below. In addition, a problem in the utilization efficiency of the laser light source has been pointed out.

[Problems in light control technology]
Since light amount control (dimming) in a laser irradiation apparatus using a conventional DMD is performed by an attenuator using light absorption, the amount of light that can be used is limited due to durability. Some attenuators use light polarization, but such attenuators have a drawback that they cannot cope with elliptically polarized light. In addition, whether it is a type that utilizes light absorption or a type that utilizes light polarization, a component having a dimension exceeding the diameter of the laser beam must be mechanically moved. There was a problem that light took time and dimming response was poor.

[Problems in film thickness control when applied to CVD]
In CVD, with the passage of time, first, particles that become nuclei are scattered on the workpiece, then lumps grow from the nuclei, and finally the lumps are connected to form a film. Is done. Therefore, even in a laser irradiation apparatus using DMD, in order to perform uniform film formation in a certain region, complicated control such as moving a workpiece on a moving stage while performing laser irradiation is performed. There was a problem that it had to be done.

[Problems in laser light source utilization efficiency]
In the laser irradiation apparatus using the conventional DMD, in order to make the influence appear in the emitted light even when any micromirror on the mirror array is in an inclined posture where the projection is turned on, always, All of the micromirrors on the mirror array were configured to be illuminated with light from a laser light source. For this reason, there has been a problem that the amount of light from the light source is consumed considerably.

  The present invention has been made paying attention to the above-mentioned problems, and the object of the present invention is to provide a sufficient amount of light to the workpiece without being restricted by the wavelength of the laser beam used. And it is providing the laser beam projection apparatus which can project the laser beam which has arbitrary cross-sectional shapes.

  Another object of the present invention is to provide a laser projection apparatus capable of dimming a laser beam at high speed regardless of the difference in polarization characteristics such as whether the laser light source is circularly polarized light or elliptically polarized light. is there.

  Another object of the present invention is to provide a laser projection apparatus capable of forming a film with a uniform film thickness on a workpiece, for example, when applied to a CVD process.

  Another object of the present invention is to provide a laser projection device capable of reducing the power consumption of a light source by not illuminating a mirror array.

  Other objects and operational effects of the present invention will be easily understood by those skilled in the art by referring to the following description of the specification.

  It is considered that the above technical problem can be solved by a laser projection apparatus having the following configuration.

  That is, the laser projection device according to the present invention includes an objective lens, a condenser lens sharing an optical axis with the objective lens, and a mirror array composed of a number of micromirrors arranged at a pitch Λ and in an initial posture. It includes a DMD in which a reference plane is defined by a reflecting surface of a series of mirror arrays, and a laser light source that illuminates the mirror array of the DMD.

  The DMD is positioned so that the reference plane forms an angle β with respect to the plane facing the condenser lens, and each of the micromirrors constituting the mirror array has an initial value corresponding to the reference plane. Switching control can be individually performed between a posture and a tilted posture inclined further by the angle α in the same direction as the angle β from the reference plane.

The laser light source is structured so as to illuminate the mirror array from a direction that forms an angle (2α + 2β) in the same direction as the angle β with respect to the optical axis. Further, the laser light source further emits light emitted from the laser light source. When the wavelength is λ,

Λ {sin (2α + β) −sinβ} = mλ

The value of the angle β is determined so that the diffraction order m satisfying the equation becomes an integer.

  According to such a configuration, since the angle β can be arbitrarily selected, the diffraction order m can always be an integer regardless of the value of the wavelength λ. Therefore, there is only one laser beam for transferring the shape, and it can be used for processing without being kicked by the objective lens. Therefore, it is possible to project a laser beam having a sufficient amount of light and an arbitrary cross-sectional shape to the workpiece without being restricted by the wavelength of the laser beam used.

  In the above-described invention, if the value of the angle β is determined so that the diffraction order m is an integer that minimizes the absolute value of the angle β, the mirror array can be a condensing lens or an objective lens. Is almost directly opposite. Therefore, the image of the mirror array is connected to the workpiece without being out of focus.

  In the above-described invention, the micromirror existing in the drawing target area on the mirror array is switched between the initial posture and the tilt posture at the substantially maximum driving frequency of the DMD, and the initial posture is changed. By manipulating the ratio between a certain time and the time in the tilted posture, the attenuation rate of light passing through the mirror array can be freely controlled. Therefore, the laser beam can be dimmed with high response regardless of the difference in polarization characteristics such as whether the laser light source is circularly polarized light or elliptically polarized light.

  In the above invention, the micromirrors existing in the drawing target area on the mirror array are divided into a plurality of micromirror blocks, and the micromirror blocks are grouped in the order of arrangement and with a predetermined delay time. By generating a wavy motion as a whole while changing the posture in units such as the initial posture, the tilt posture, and the initial posture, the micromirror mass in the tilt posture is moved at a predetermined speed in the drawing target area. For example, a film forming process having a uniform film thickness can be realized by a process such as CVD.

  Furthermore, the drawing target area is divided into a plurality of small areas, and the wavy motion is generated for each small area, so that a plurality of micromirror masses in the inclined posture are simultaneously formed in the drawing target area. If it moves, by simultaneously scanning light in a plurality of regions of the workpiece, it is possible to execute the processing in parallel, thereby shortening the processing time.

  Furthermore, in the above-described invention, by interposing a beam scanning mechanism between the laser light source and the DMD, an arbitrary micromirror or micromirror group is selectively selected from among the micromirrors constituting the mirror array. By enabling illumination, it is possible to reduce the power consumption of the light source by eliminating wasted light.

  Since the laser projection apparatus according to the present invention has an arbitrarily selectable parameter such as the angle β, the diffraction order m can always be an integer. Therefore, there is only one laser beam for transferring the shape, and it can be used for processing without being kicked by the objective lens. Therefore, it is possible to project a laser beam having a sufficient amount of light and an arbitrary cross-sectional shape to the workpiece without being restricted by the wavelength of the laser beam used.

  Hereinafter, a preferred embodiment of a laser projection apparatus according to the present invention will be described in detail with reference to the accompanying drawings.

  A block diagram of a first embodiment of a laser projection apparatus (laser CVD apparatus) according to the present invention is shown in FIG. As shown in the figure, this laser projection device 100 is a laser light source (including both the light source itself and the illumination optical system in this example) 1 that emits a laser beam that is the optical axis B1, and a processing target. A workpiece table 8 on which the workpiece is placed, and a reference plane (defined by the reflecting surfaces of a series of micromirrors in an initial posture) P4 that is directly above the workpiece table 8 and that is horizontal. DMD 2 disposed at an angle β clockwise with respect to P 3, a photodetector 6 for monitoring a projection laser beam necessary for calculating an attenuation factor, which will be described later, and light that is not used for processing can be safely used. It has a laser absorber 7 for converting it into heat, and a gas supply device 5 for supplying a CVD source gas to a processing location of a workpiece (not shown) on the workpiece table 8.

  A front view of the DMD 2 viewed from the light receiving surface side is shown in FIG. As shown in the figure, a large number of micromirrors 21 are arranged on the substrate 2a of the DMD 2 with a pitch v in the vertical direction, a pitch w in the horizontal direction, and a pitch Λ in the diagonal direction. In addition, this mirror array is arranged on the DMD 2 so that the diagonal direction of each micromirror 21 corresponds to the inclination direction of the angle β (left and right direction in FIG. 1).

  A schematic cross-sectional view illustrating the arrangement of the micromirrors 21 on the DMD 2 is shown in FIG. As shown in the figure, the DMD 2 is inclined such that its reference plane P4 forms an angle β clockwise with respect to a plane (that is, a horizontal plane) P3 that faces the condenser lens 3 (see FIG. 1). Positioned in posture.

  Each of the micromirrors 21 constituting the mirror array arranged on the substrate has an initial posture parallel to the reference plane P4 (corresponding to the micromirror 21a), and is tilted by an angle α clockwise from the reference plane P4. 1 according to an electrical signal applied from the outside, corresponding to an inclination posture of 1 (corresponding to the micromirror 21b) and a second inclination posture (corresponding to the micromirror 21c) inclined counterclockwise from the reference plane P4 by an angle α. Therefore, switching control can be performed individually.

  The laser light source 1 (see FIG. 1) has a predetermined beam diameter from a direction (direction of the optical axis B1) that makes an angle (2α + 2β) clockwise with respect to the optical axis B12 of the condenser lens 3 (see FIG. 1). It is designed to illuminate the mirror array of DMD 2 with a laser beam.

Here, the value of the angle β is obtained when the wavelength of light emitted from the laser light source 1 (see FIG. 1) is λ,

Λ {sin (2α + β) −sinβ} = mλ

The diffraction order m satisfying the above relationship is determined to be an integer. Here, m is the diffraction order, and λ is the wavelength of the light emitted from the laser light source 1. Also, Λ is

Λ ² = v ² + w ²

λ = 0.349μm

p ¹ = p ² = 13.68 μm

The pitch in the diagonal direction of the micromirror calculated by (see FIG. 2).

  In the above formula, there are a plurality of values of the angle β such that the value of the diffraction order m is an integer. In particular, the value of the angle β in this embodiment is an angle β such that the diffraction order m is an integer. Among them, the one having the smallest absolute value is selected.

  The operational effects of the laser projection apparatus (first embodiment) having the above-described configuration will be described as follows.

  When the reference plane P4 of the mirror array is tilted clockwise by an angle β with respect to the plane P3 facing the objective lens 3, the micromirror 21b in the first tilted posture is perpendicular (the optical axis of the objective lens 3). Direction) When light is incident from a direction inclined by an angle (2α + 2β) clockwise with respect to P1, the relationship of “incident angle = reflection angle = α + β” is established, and therefore a perpendicular line (the optical axis of the objective lens 3). Direction) The power is most easily deflected in the direction of P1.

However, if the beam diameter of the incident light is sufficiently larger than the dimensions of the micromirrors 21, the reflected lights of the micromirrors 21 interfere with each other. Therefore, considering the line P6 orthogonal to the reference plane P4 of the mirror array as a reference, Since “incident angle = 2α + β” and “exit angle = β”,

Λ {sin (2α + β) −sinβ} = mλ

Diffracted light is generated in the direction satisfying the above.

  FIG. 9 conceptually shows an explanatory diagram of the diffracted beam obtained when the DMD is laser-illuminated. If the DMD reference plane P4 is not tilted at all with respect to the plane P3 facing the objective lens as shown in FIG. 5A, or if the DMD reference plane P4 is set as shown in FIG. When the angle 2β is inclined, a plurality of diffracted beams having an angle θ with respect to each other are generated discretely, but two of these beams having relatively large power are both optical axes B12 of the condenser lens 3. Since the laser beam travels in a direction deviating left and right, the power of the laser beam cannot be effectively used for the processing.

  On the other hand, as shown in FIG. 4B, when the reference plane P4 of the DMD is inclined by an angle β with respect to the plane P3 facing the objective lens, a plurality of diffraction beams having an angle θ with respect to each other. However, since one beam having the largest power travels in the direction of the optical axis B12 of the condenser lens 3, it is possible to effectively utilize the power of the laser beam for processing. it can.

  As shown in FIG. 4D, even when the DMD reference plane P4 is inclined at an angle 3β with respect to the plane P3 facing the objective lens, one beam having the largest power is condensed. Although it proceeds in the direction of the optical axis B12 of the lens 3, the power of the beam is clearly inferior to that when the angle β is inclined.

  As described above, according to the present invention, since the angle β can be arbitrarily selected, the diffraction order m can always be an integer regardless of the value of the wavelength λ. Therefore, there is only one laser beam for transferring the shape, and it can be used for processing without being kicked by the objective lens 4 (see FIG. 1). Therefore, it is possible to project a laser beam having a sufficient amount of light and an arbitrary cross-sectional shape to the workpiece without being restricted by the wavelength of the laser beam used.

  In addition, since the value of the angle β is determined so that the diffraction order m is an integer that minimizes the absolute value of the angle β, the mirror array includes the condenser lens 3 (see FIG. 1) and the objective lens 4. (Refer to FIG. 1). Therefore, there is an advantage that the image of the mirror array (the pattern of the micromirror in the second tilted posture) is formed on the workpiece without being out of focus.

  Here, since the micro mirror 21a in the initial posture has an inclination angle of 0 with respect to the reference plane P3, the reflected diffracted light travels along the optical axis B11 toward the photodetector 6 (see FIG. 1), and the laser It is used for beam monitoring. Further, since the micro mirror 21b in the first tilt posture is tilted by the angle α clockwise with respect to the reference plane P3, the reflected diffracted light travels along the optical axis B12, and the condensing lens 3 (FIG. 1) and subjected to the CVD process. Further, since the micro mirror 21c in the second tilted posture is tilted by the angle α counterclockwise with respect to the reference plane P3, the reflected diffracted light travels along the optical axis B13, and the light absorber 7 generally. Therefore, light that is not used for processing is safely converted into heat by the light absorber 7.

  Next, a novel dimming control in the laser projection apparatus using the DMD described above will be described.

  As described above, conventionally, in a laser transfer apparatus using this type of DMD, in order to adjust the intensity of a laser beam projected on a non-workpiece, an attenuator using light absorption has been adopted. Therefore, the amount of light that can be used is limited due to durability. Further, some attenuators use a type of polarization of light, but such attenuators have a drawback that they cannot cope with elliptically polarized light. In addition, whether it is a type that utilizes light absorption or a type that utilizes light polarization, a component having a dimension exceeding the diameter of the laser beam must be mechanically moved. There was a problem that light took time and dimming response was poor.

  Therefore, the present inventor tilts the micromirror belonging to the range of the shape to be transferred to the workpiece to the right by focusing on the DMD itself, not by the attenuator using such light absorption. A method is proposed in which the amount of light used for processing is adjusted by making a high-speed transition (at approximately the maximum drive frequency of the DMD) between a tilted state (first tilt posture) and a non-tilt state (initial posture).

  At this time, the attenuation rate can be set as “(time when tilted to the right) ÷ {(time when tilted to the right) + (time not tilted)}”. (Power detected by the light detector 6 during processing) / (Power detected by the light detector 6 during the stop) ”.

  According to such a dimming method, it is possible to freely control the attenuation rate of light passing through the mirror array on the DMD without sliding control of the light absorbing plate interposed in the optical path or adjusting the polarization characteristics. Regardless of the difference in polarization characteristics such as whether the laser light source is circularly polarized light or elliptically polarized light, the laser beam can be dimmed with high response, and the processing accuracy in processing by laser projection can be improved.

  Next, an explanatory diagram showing a first operation mode of the mirror array in the first embodiment is shown in FIG. The micromirror in the region surrounded by the contour line 22 corresponding to the drawing range on the workpiece is filled with hatching. The micromirrors that contribute to these processes are the micromirrors 21b in the second tilt attitude, and the other micromirrors are the micromirrors 21c in the third tilt attitude, so that the target workpiece An object can be CVD processed into a “U” shape.

  Next, an explanatory diagram showing a second operation mode of the mirror array in the first embodiment is shown in FIG. FIGS. 9A to 9C show the operating states of the micromirrors at a certain time separated by a certain time. In this example, the micromirrors in the region (drawing target region) surrounded by the contour line 22 corresponding to the drawing range on the workpiece are not collectively set to the second tilt posture, As shown by the arrows 23, 24, 25 and hatching inside, by tilting the predetermined number of micromirrors in the region surrounded by the contour line 22 in order, The CVD process is performed in a letter shape.

  That is, the micromirrors existing in the drawing target area on the mirror array are divided into a plurality of micromirror blocks, and the micromirror blocks are arranged in the order of the arrangement and with a predetermined delay time, in a unit of block, the initial posture, By generating a wave-like motion as a whole while changing the posture such as the tilt posture and the initial posture, the micromirror mass in the tilt posture moves at a predetermined speed in the drawing target region. Further, particularly in this example, the drawing target area is partitioned into a plurality of small areas, and a plurality of wavy motions are generated for each small area, so that the drawing target area has a plurality of inclination postures. The micromirror mass moves at the same time.

  According to such an operation mode of the micromirror, the deposit grows in the in-plane direction, so that a uniform film can be obtained. When the film is used for electrical wiring, a homogeneous film is particularly effective for reducing the resistance value. In addition, by simultaneously scanning light in a plurality of regions of the workpiece, it is possible to execute the processing in parallel, thereby shortening the processing time.

  FIG. 10 is an explanatory diagram showing how a metal grain boundary grows in the CVD process, and FIG. 11 is an explanatory diagram showing the nature of the grain boundary of the metal.

  As shown in FIG. 10 (a), when laser beam irradiation is performed on the substrate in the presence of gaseous metal, as shown in FIG. 10 (b), intermolecular bonds of gaseous metal are caused by ultraviolet rays. Then, the metal powder falls on the substrate, and then, as shown in FIG. 5C, the metal powder adhered to the substrate is used as a shell, and the gas metal decomposed by the heat of the laser. Grain boundaries will grow.

  At this time, as shown in FIG. 11A, when the substrate is made stationary with respect to the laser, the grain boundary grows at right angles to the substrate, and the grown grain boundary has a large thickness. The electrical resistance becomes high. On the other hand, as shown in FIG. 5B, when the substrate is moved with respect to the laser, the grain boundary grows parallel to the substrate, and the grown grain boundary has a thickness. The electrical resistance is low.

  Therefore, as described above, since the deposit grows in the in-plane direction by inclining a predetermined number of micromirrors in the region surrounded by the contour line 22 in order, a homogeneous film can be obtained. is there.

  In the above first embodiment, a laser projection apparatus suitable for CVD has been shown, but by selecting the power and wavelength of the laser light source, the workpiece can be heated, melted, vaporized in any shape, Of course, processing such as cutting and exposure recording can be performed.

  As an example of the first embodiment described above, the following specific modes can be cited. That is, a third harmonic of a YLF laser is used as the laser light source 1, and a DMD product of Texas Instruments Inc. of the United States can be used as the DMD 2 having a mirror array. The inclination angle β with respect to the plane (horizontal plane) P3 facing the optical axis B12 of the reference plane P4 of the DMD 2 can be selected to be 5 degrees.

At this time, as shown in the following equation, since only the 22nd order is excited, only one diffracted light beam is generated and efficiently passes through the pupil of the objective lens. Reaches the work piece.

α = 12 °

β = 5 °

Ｍ m = 22.0

  The block diagram of 2nd Embodiment of the laser projection apparatus (laser CVD apparatus) based on this invention is shown by FIG. The second embodiment is characterized in that the galvano mirrors 9a and 9b are interposed between the laser light source 1 and the DMD 2 to reduce the beam power by using a small-diameter laser beam, while at the same This area can be illuminated.

  That is, as shown in FIG. 6, the light emitted from the laser light source 1 passes through the galvanometer mirrors 9a and 9b, is shifted in parallel by an arbitrary interval, and is irradiated onto the mirror array on the DMD 2, and the arbitrary Illuminate the spot. Therefore, an arbitrary area on the mirror array can be illuminated by appropriately controlling the galvanometer mirrors 9a and 9b.

  Next, an explanatory diagram showing a first operation mode of the mirror array in the second embodiment is shown in FIG. As shown in the figure, the spot 26 of the illumination laser beam has a circular shape whose diameter is sufficiently smaller than the vertical and horizontal lengths of the mirror array, and is controlled by the galvanometer mirrors 9a and 9b. It is possible to move to the position. In the example of FIG. (A), the substantially central part of the mirror array is illuminated by the spot 26, and in the example of FIG. (B), the vicinity of the corner of the mirror array is illuminated. In the figure, 21b is a micromirror in the second tilted posture, and 21c is a micromirror in the third tilted posture.

  By illuminating the micromirror in the region surrounded by the contour line 22 corresponding to the drawing range on the workpiece with the spot 26 of the laser beam for illumination, the micromirror is surrounded by the contour line 22 as shown by hatching in the figure. It is possible to simultaneously illuminate the micromirrors 21b in the second tilt posture existing in the region.

  At this time, the position of the beam spot 26 can be instantaneously moved between the state of FIG. 7A and the state of FIG. 7B by electrical angle control with respect to the galvanometers 9a and 9b. According to the second embodiment, it is possible to perform CVD processing at a plurality of locations at extremely high speed while reducing the power of the illumination beam.

  An explanatory diagram showing a second operation mode of the mirror array in the second embodiment is shown in FIG. In the figure, 21b is a micromirror in the second tilted posture, and 21c is a micromirror in the third tilted posture.

  As shown in FIG. 8A, in this example, the contour line 22 corresponding to the drawing range on the workpiece has a U-shape so as to cover the entire area of the mirror array. Even in such a case, a small-diameter illumination beam spot 26a capable of irradiating only four micromirrors 21 at the same time is prepared, and the beam spot 26a is moved into the U-shaped region 22 so that FIG. As shown in (b), the entire U-shaped region 22 is filled as indicated by the envelope 27 of the moving beam spot.

In this example, as shown in FIG. 8C, if the beam spot scanning speed has a margin, the scanning range is further increased by scanning with a smaller beam spot as shown in the scanning beam spot 26b. The amount of wasted light can be reduced, and processing that requires high energy density can also be handled.
In addition, the dimming technology described above, the CVD processing technology using the wave operation, and the local irradiation technology of the mirror array by the galvanometer are used in the conventional laser irradiation apparatus that does not adopt the inclination control of the angle β by using the recommended value of the wavelength λ. Of course, it is applicable.

  According to the present invention, in a laser projection apparatus using a DMD, a laser beam having a sufficient amount of light for a workpiece and having an arbitrary cross-sectional shape without being restricted by the wavelength of the laser beam used. Can be projected.

It is a lineblock diagram of a 1st embodiment of a laser projection device (laser CVD device) concerning the present invention. It is the front view seen from the light-receiving surface side of DMD. It is typical sectional drawing explaining the arrangement | sequence of the micromirror on DMD. It is explanatory drawing which shows the 1st operation | movement aspect of the mirror array in 1st Embodiment. It is explanatory drawing which shows the 2nd operation | movement aspect of the mirror array in 1st Embodiment. It is a block diagram of 2nd Embodiment of the laser projection apparatus (laser CVD apparatus) which concerns on this invention. It is explanatory drawing which shows the 1st operation | movement aspect of the mirror array in 2nd Embodiment. It is explanatory drawing which shows the 2nd operation | movement aspect of the mirror array in 2nd Embodiment. It is explanatory drawing of the diffracted beam obtained when laser illuminating DMD. It is explanatory drawing which shows a mode that the grain boundary of a metal grows in a CVD process. It is explanatory drawing which shows the property of the grain boundary of the metal grown by CVD process. It is explanatory drawing which shows an example of the conventional laser projection apparatus. It is a block diagram of the conventional laser CVD apparatus which is one of the laser projection apparatuses.

Explanation of symbols

1 Laser light source 2 DMD
DESCRIPTION OF SYMBOLS 3 Condensing lens 4 Objective lens 5 Gas supply instrument 6 Photo detector 7 Optical absorber 8 Workpiece table 9a, 9b Galvano mirror B1 Optical axis of illumination light with respect to DMD B11 First reflected light (monitor light) from DMD Optical axis B12 Optical axis of second reflected light (projection light) from DMD B13 Optical axis of third reflected light (unused light) from DMD 21 Micromirror 21a Micromirror 21b in initial posture 21b In first tilt posture A certain micromirror 21c A micromirror in the second tilt posture 22 An outline of the illumination area on the mirror array 23, 24, 25 An arrow indicating the moving direction of the micromirror in the first tilt posture 26 A laser beam spot for illumination 26a Laser beam spot for illumination 26b Laser beam spot for small-diameter illumination 27 Irradiation area by beam spot scanning Overall 100 Laser irradiation device v Micro-mirror vertical pitch w Micro-mirror horizontal pitch Λ Micro-mirror diagonal pitch P1 Line perpendicular to the horizontal plane (surface facing the condensing lens) P2 Micro-mirror A line perpendicular to the reflecting surface P3 A line indicating a horizontal plane (a plane facing the condenser lens) P4 A line indicating an angle β with respect to the horizontal plane (a plane facing the condenser lens) P5 An angle with respect to the horizontal plane A line indicating a surface forming an angle α with respect to a surface forming β

Claims (10)

An objective lens;
A condenser lens sharing an optical axis with the objective lens;
A DMD in which a mirror array composed of a large number of micromirrors is arranged at a pitch Λ, and a reference plane is defined by a reflecting surface of a series of mirror arrays in an initial posture;
A laser light source for illuminating the mirror array of the DMD,
The DMD is
The reference plane is positioned so as to form an angle β with respect to the surface facing the condenser lens, and each of the micromirrors constituting the mirror array has an initial posture corresponding to the reference plane, and It is possible to individually control switching from a reference plane to an inclination posture that is further inclined by an angle α in the same direction as the angle β.
The laser light source is
It is structured to illuminate the mirror array from a direction that forms an angle (2α + 2β) in the same direction as the angle β with respect to the optical axis, and the wavelength of light emitted from the laser light source is λ. When

Λ {sin (2α + β) −sinβ} = mλ

The laser irradiation apparatus is characterized in that the value of the angle β is determined so that the diffraction order m satisfying the above becomes an integer.   2. The laser irradiation apparatus according to claim 1, wherein the value of the angle β is determined so that the diffraction order m is an integer that minimizes the absolute value of the angle β.   The micromirrors existing in the drawing target area on the mirror array are switched between the initial posture and the tilt posture at approximately the maximum driving frequency of the DMD, and the time and tilt posture in the initial posture are changed. The laser irradiation apparatus according to claim 1, wherein an attenuation rate of light passing through the DMD is controlled by manipulating a ratio with a certain time.   The micromirrors present in the drawing target area on the mirror array are divided into a plurality of micromirror blocks, and the micromirror blocks are arranged in the order of the arrangement and with a predetermined delay time, the initial posture and inclination in units of blocks. The micromirror mass in the tilted posture moves at a predetermined speed in the drawing target region by generating a wavy motion as a whole while changing the posture such as the posture and the initial posture. Item 4. The laser irradiation apparatus according to any one of Items 1 to 3.   The drawing target area is divided into a plurality of small areas, and the plurality of micromirror masses in the inclined posture simultaneously move in the drawing target area by generating the wavy motion for each small area. The laser irradiation apparatus according to claim 4, which is configured as described above.   By interposing a beam scanning mechanism between the laser light source and the DMD, it is possible to selectively illuminate an arbitrary micromirror or a group of micromirrors among the micromirrors constituting the mirror array. The laser irradiation apparatus according to claim 1, wherein the apparatus is a laser irradiation apparatus. An objective lens;
A condenser lens sharing an optical axis with the objective lens;
A DMD in which a mirror array composed of a large number of micromirrors is arranged at a pitch Λ, and a reference plane is defined by a reflecting surface of a series of mirror arrays in an initial posture;
A laser light source for illuminating the mirror array of the DMD,
Each of the micromirrors constituting the mirror array can be individually switched and controlled between an initial attitude corresponding to the reference plane and an inclination attitude inclined by an angle α with respect to the reference plane.
The micromirrors existing in the drawing target area on the mirror array are switched between the initial posture and the tilt posture at approximately the maximum driving frequency of the DMD, and the time and tilt posture in the initial posture are changed. A laser irradiation apparatus characterized by controlling an attenuation rate of light passing through the DMD by manipulating a ratio with a certain time.   The micromirrors present in the drawing target area on the mirror array are divided into a plurality of micromirror blocks, and the micromirror blocks are arranged in the order of the arrangement and with a predetermined delay time, the initial posture and inclination in units of blocks. The micromirror mass in the tilted posture moves at a predetermined speed in the drawing target region by generating a wavy motion as a whole while changing the posture such as the posture and the initial posture. Item 8. The laser irradiation apparatus according to Item 7.   The drawing target area is divided into a plurality of small areas, and the plurality of micromirror masses in the inclined posture simultaneously move in the drawing target area by generating the wavy motion for each small area. The laser irradiation apparatus according to claim 7, wherein the laser irradiation apparatus is configured as described above. An objective lens;
A condenser lens sharing an optical axis with the objective lens;
A DMD in which a mirror array composed of a large number of micromirrors is arranged at a pitch Λ, and a reference plane is defined by a reflecting surface of a series of mirror arrays in an initial posture;
A laser light source for illuminating the mirror array of the DMD,
Each of the micromirrors constituting the mirror array can be individually switched and controlled between an initial attitude corresponding to the reference plane and an inclination attitude inclined by an angle α with respect to the reference plane.
By interposing a beam scanning mechanism between the laser light source and the DMD, it is possible to selectively illuminate an arbitrary micromirror or a group of micromirrors among the micromirrors constituting the mirror array. A featured laser irradiation device.

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