JP2020047684A - Light source device and line beam homogenizer using the same - Google Patents

Abstract

To provide a light source device that can emit a laser beam light with reduced coherence using a laser light source that emits a laser beam light with high coherence without the electric field intensity at the focal point reaching the intensity limit.SOLUTION: A light source device 100 having a laser light source 10 that emits laser beam light includes a diffusion optical system 12 that converts the laser beam light from the laser light source 10 into a diffusion laser beam light having a predetermined diffusion angle, and an emission optical system 13 that emits the diffusion laser beam light from the diffusion optical system 12 as the emission laser beam light from the light source device 100.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a light source device provided with a laser light source that emits laser beam light, and a line beam homogenizer using the light source device.

  Conventionally, a laser annealing apparatus described in Patent Document 1 is known. In this laser annealing apparatus, a light source device including a laser light source (for example, a solid-state laser) that emits a laser beam and a beam expander that enlarges the diameter of the laser beam from the laser light source is used. Then, from such a light source device and laser beam light of a predetermined spot size emitted from the light source device, the energy distribution was made uniform in both the major axis direction and the minor axis direction orthogonal to the major axis direction. A line beam homogenizer is constituted by the homogenizing optical system (long axis homogenizer, short axis homogenizer) for generating the linear laser beam light extending in the long axis direction.

  In the laser annealing apparatus having the above-described line beam homogenizer, the linear laser beam light formed by the homogenizing optical system scans the surface of the amorphous semiconductor film in the short axis direction. The surface of the amorphous semiconductor film is annealed by the thermal energy of the linear laser beam that scans the surface of the amorphous semiconductor film in the short axis direction. As a result, the surface of the amorphous semiconductor film is polycrystallized.

JP 2009-16541 A

  In the light source device used for the line beam homogenizer as described above, the coherency of the laser beam emitted from the laser light source is high. By utilizing such high energy of the laser beam light having high coherence, the annealing process can be effectively performed.

  On the other hand, such a laser beam having high coherence has a high light-collecting property. For this reason, for example, when the laser beam is converged to one point by an optical system disposed downstream of the laser light source, for example, a spherical convex lens of a telescope included in the beam expander, the electric field intensity at the converging point May reach the intensity limit (breakdown), and the laser beam may not proceed any further.

  In the homogenizing optical system, for example, the laser beam light is dispersed by each lens of the lens array, and the dispersed laser beam light is superimposed, so that the energy distribution of the formed linear laser beam light is made uniform. (Dispersion type homogenizer). When a laser beam having extremely high coherence is incident on such a homogenizing optical system, interference fringes may occur, and the uniformity of the energy distribution of the formed linear laser beam is rather hindered. There is a risk.

  The present invention has been made in view of such circumstances, and uses a laser light source that emits a laser beam with high coherence to reduce the coherence without causing the electric field intensity at the focal point to reach the intensity limit. An object of the present invention is to provide a light source device that can emit a laser beam light that has been relaxed.

  The present invention also provides a line beam homogenizer using the above light source device.

  A light source device according to the present invention is a light source device having a laser light source that emits a laser beam light, and a diffusion optical system that converts the laser beam light from the laser light source into a diffusion laser beam light having a predetermined diffusion angle. And an emission optical system that emits the diffused laser beam from the diffusion optical system to the emitted laser beam from the light source device.

  According to such a configuration, the coherency of the laser beam from the laser light source is reduced by the diffusion optical system, and the laser beam is converted into a diffusion laser beam having a predetermined diffusion angle. Then, the diffused laser beam light having reduced coherence from the diffusion optical system is emitted as emission laser beam light via the emission optical system.

  In the light source device according to the present invention, the diffusion angle of the diffused laser beam light is larger than the diffusion angle of the laser beam light emitted from the laser light source, and all of the diffused laser beam light from the diffusion optical system is used. The angle can be equal to or less than the maximum diffusion angle that can be incident on the emission optical system, and more specifically, can be set to a value within the range of 10 ± 5 mrad.

  In the light source device according to the aspect of the invention, the emission optical system may include a beam expansion optical system that expands a light diameter of the diffused laser beam light from the diffusion optical system and emits a laser beam light having the expanded light diameter. Including, can be a configuration.

  According to such a configuration, in the emission optical system, when the diffused laser beam light from the diffusion optical system enters the beam expansion optical system, the beam diameter of the diffusion laser beam is expanded by the beam expansion optical system, The laser beam having the enlarged light diameter is emitted from the beam expanding optical system. Since the light diameter of the outgoing beam light is enlarged from the light diameter of the incident beam light (diffusion laser beam light), as a result, the diffusion angle of the outgoing light beam becomes the diffusion angle of the incident beam light (diffusion laser beam light). Can be changed (smaller).

  In the light source device according to the present invention, there is provided a light beam stabilizing device for stabilizing the energy by suppressing temporal fluctuation of the energy of the laser beam light from the laser light source, and the laser beam passing through the light energy stabilizing device. Light may be incident on the diffusion optical system.

  According to such a configuration, the energy of the laser beam light from the laser light source is stabilized, so that the energy of the laser beam light that has passed through the diffusion optical system and the emission optical system can be stabilized. The energy of the laser beam emitted from the light source device can be stabilized.

  In the light source device according to the present invention, the light energy stabilizing device is obtained by a beam splitter that splits the laser beam from the laser light source into a first beam and a second beam, and the beam splitter. A delay optical system for delaying the first light beam, an energy detector for detecting an energy value of the second light beam obtained by the beam splitter, and the second light beam detected by the energy detector And stabilizing the energy of the first light beam from the delay optical system based on the energy value of the first light beam. The first light beam whose energy is stabilized by the stabilizer is The light may be incident on the diffusion optical system.

  According to such a configuration, the laser beam from the laser light source is split into the first beam and the second beam by the beam splitter. While the first light beam enters the delay optical system, the energy value of the second light beam is detected by an energy detector. Then, the energy of the first light beam having passed through the delay optical system is stabilized based on the energy value of the second light beam detected by an energy detector. Then, the first light beam whose energy is stabilized enters the diffusion optical system.

  The delay characteristic (for example, delay time) of the light in the delay optical system can be determined based at least on the temporal operation characteristic of the stabilizer.

  In the light source device according to the present invention, the stabilizer includes a variable light attenuation optical system having a variable attenuation rate, through which the first light beam from the delay optical system passes, and the energy detector detects the variable light attenuation optical system. The controller may be configured to increase the attenuation value in the variable optical attenuation optical system as the energy value to be performed increases.

  According to such a configuration, the first light beam from the delay optical system is attenuated by the variable light attenuating optical system as the energy value of the second light beam detected by the energy detector increases. This stabilizes the energy of the first light beam constituting the laser light beam from the laser light source together with the second light beam.

  A light source device according to the present invention is a light source device including a laser light source that emits a laser beam light, wherein the beam splitter divides the laser beam light from the laser light source into a first beam light and a second beam light. A delay optical system for delaying the first light beam obtained by the beam splitter, an energy detector for detecting an energy value of the second light beam obtained by the beam splitter, and the energy detector A stabilizer for stabilizing the energy of the first light beam from the delay optical system based on the detected energy value of the second light beam, wherein the energy is stabilized by the stabilizer. The first light beam thus emitted is emitted.

  According to such a configuration, the laser beam from the laser light source is split into the first beam and the second beam by the beam splitter, and the first beam enters the delay optical system, The energy value of the light is detected by an energy detector. Then, with respect to the first light beam that has passed through the delay optical system, a temporal change in the energy is suppressed based on the energy value of the second light beam detected by the energy detector, and the energy is stabilized. . The first beam light whose energy is stabilized is emitted as an emitted laser beam light.

  In the light source device according to the present invention, the stabilizer includes a variable light attenuation optical system having a variable attenuation rate, through which the first light beam from the delay optical system passes, and the energy detector detects the variable light attenuation optical system. A controller that increases the attenuation rate in the variable light attenuation optical system as the energy value to be performed is larger.

  In addition, the line beam homogenizer according to the present invention includes any one of the light source devices described above, and both the long axis direction and the short axis direction orthogonal to the long axis direction from the laser beam emitted from the light source device. And a homogenizing optical system that generates a linear laser beam that extends in the long axis direction and has a uniform energy distribution.

  According to such a configuration, the energy distribution in both the major axis direction and the minor axis direction is homogenized from the laser beam light (emission laser beam light) from the light source device whose coherence is reduced by the diffusion optical system. , And a linear laser beam extending in the long axis direction is generated.

  According to the light source device of the present invention, since the coherence of the laser beam emitted from the laser light source is reduced, the intensity of the electric field at the focal point does not reach the intensity limit, and the coherence is reduced. Beam light (emitted laser beam light) can be emitted.

  Further, according to the line beam homogenizer according to the present invention, the electric field intensity at the focal point does not reach the intensity limit, and the laser beam light with reduced coherence is used in both the long axis direction and the short axis direction. , A linear laser beam having a uniform energy distribution is formed. Thereby, more stable linear laser beam light can be obtained.

FIG. 1 is a block diagram showing a configuration of a line beam homogenizer according to one embodiment of the present invention. FIG. 2 is a diagram showing a diffusion optical system (diffusion plate) included in the light source device in the line beam homogenizer shown in FIG. FIG. 3 is a diagram showing an enlarged optical system included in the light source device in the line beam homogenizer shown in FIG. FIG. 4 is a diagram showing the relationship between the magnification (magnification ratio) and the diffusion angle by the magnifying optical system (emission optical system) shown in FIG. FIG. 5 is a diagram showing a configuration of a light energy stabilizing device included in the light source device in the line beam homogenizer shown in FIG. FIG. 6 is a diagram showing a configuration of a variable light attenuation optical system in the light energy stabilizing device shown in FIG. FIG. 7 is a timing chart showing the temporal operation characteristics of the variable optical attenuation optical system (high-speed optical switch element (AOE)) shown in FIG. 6 in relation to the detection timing of the pulsed first laser beam light. . FIG. 8 is a diagram showing the operation of the variable light attenuation optical system in relation to the energy value of the incident laser beam light. FIG. 9 is a diagram showing a basic configuration of a long axis homogenizer. FIG. 10 is a diagram showing characteristics of long-axis light intensity by the long-axis homogenizer shown in FIG. FIG. 11 is a diagram showing a basic configuration of the short-axis homogenizer. FIG. 12 is a diagram showing a configuration of a short axis reduction projection lens system.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  A line beam homogenizer according to one embodiment of the present invention is configured as shown in FIG. In FIG. 1, the line beam homogenizer includes a light source device 100 having a solid-state UV pulse laser 10 as a laser light source, a long-axis homogenizer 14, a short-axis homogenizer 15, and a short-axis reduction projection lens system 16 And The long axis homogenizer 14 makes the energy distribution in the long axis direction of the laser beam light LB4 emitted from the light source device 100 uniform. The short-axis homogenizer 15 equalizes the energy distribution of the laser beam LB5 passing through the long-axis homogenizer 14 in the short-axis direction orthogonal to the long-axis direction. The short axis reduction projection lens system 16 reduces the spot size of the laser beam LB6 that has passed through the short axis homogenizer 15 in the short axis direction. As described above, the laser beam light LB4 emitted from the light source device 100 passes through the long-axis homogenizer 14 and the short-axis homogenizer 15 (homogenizing optical system) and the short-axis reduction projection lens system 16, so that the long-axis direction is obtained. A linear laser beam LB7 extending in the long axis direction and having a uniform energy distribution in both the short axis direction and the short axis direction is generated.

  The light source device 100 includes, in addition to the solid-state UV pulse laser 10 as a laser light source, a light energy stabilizing device 11, a diffusion optical system 12, and a beam expanding optical system 13 (beam expander: emission optical system). I have. The light energy stabilizing device 11 suppresses the temporal fluctuation of the energy of the laser beam light LB1 having a frequency in a UV band (ultraviolet band) emitted in a pulse form from the solid-state UV pulse laser 10 (laser light source), and the energy is reduced. The stabilized laser beam light LB2 is emitted. The diffusion optical system 12 diffuses the laser beam light LB2 that has passed through the light energy stabilizing device 11 into a diffusion laser beam LB3 having a predetermined diffusion angle. The beam expanding optical system 13 (emission optical system) uses the laser beam light having a light diameter larger than the light diameter of the diffused laser beam light LB3 incident from the diffusion optical system 11 as the emitted laser beam light LB4 of the light source device 100. Into the long axis homogenizer 14 (homogenizing optical system).

  The specific configuration of each part of the light source device 100 will be described.

  The specific configuration of the light energy stabilizing device 11 for stabilizing the energy of the laser beam light LB1 from the solid-state UV pulse laser 10 will be described later. First, the diffusion optical system 11 includes a diffusion plate 121 as shown in FIG. The diffusion plate 121 has a structure in which a fine concavo-convex pattern (holographic pattern) is formed on a surface of a transparent substrate formed of a resin such as an epoxy resin, for example. The laser beam light LB2 from the light energy stabilizing device 11 that is incident with the beam light diameter Φ1 is diffused by the diffusion plate 121 and is spread on the incident surface S1 of the beam expanding optical system 13 with the beam light diameter Φ2 (≧ Φ1). Light beam LB3 is incident.

  The diffusion angle of the diffused laser beam LB3 is larger than the diffusion angle of the laser beam LB2 emitted from the light energy stabilizing device 11, that is, the diffusion angle of the laser beam LB1 from the solid-state UV pulse laser 10 (for example, The angle is larger than 0.26 degrees (4.5 milliradians), and all of the diffused laser beam LB3 from the diffuser plate 121 is smaller than the maximum diffusion angle that can be incident on the incident surface S1 of the beam expanding optical system 13. Specifically, the diffusion angle is preferably set to a value within a range of 10 ± 5 mrad from the viewpoint of suppressing coherence without significantly impairing the energy concentration of the laser beam. For example, when the diffusion angle θ is 0.5 degrees (about 9 milliradians), the laser beam LB2 that is incident on the diffusion plate 121 at a beam light diameter Φ1 of 6 mm is 45 centimeters (L = 45 cm) away from the diffusion plate 121. The divergent laser beam LB3 having a beam diameter of Φ2 ≒ 10 mm is incident on the incident surface S1 of the beam expanding optical system 13.

  Next, as shown in FIG. 3, the beam expanding optical system 13 (beam expander: emission optical system) includes two convex lenses and a first convex lens 131 which are parallel to each other and arranged in series in the optical axis direction. And a second convex lens 132. The diffused laser beam light LB3 from the above-described diffuser plate 121 is incident on the first convex lens 131 (the incident surface S1 of the beam expanding optical system 13) and is condensed on the converging point P (focal point). Then, the laser beam light diverging from the converging point P enters the second convex lens 132, and is emitted from the second convex lens 132 as a laser beam LB4 (emitted laser beam light).

  By the enlargement function based on the optical characteristics (focal length and the like) of the first convex lens 131 and the second convex lens 132 constituting the telescope described above, the light diameter of the incident diffused laser beam LB3 on the incident surface S1 is enlarged. The laser beam having the enlarged light diameter is emitted from the beam expanding optical system 13 as the laser beam LB4 emitted from the light source device 100. As described above, the light diameter of the outgoing beam light (laser beam light LB4) is expanded from the light diameter of the incident beam light (diffused laser beam light LB3), and as a result, the outgoing beam light (laser beam light LB4) is diffused. The angle can be changed (decreased) from the divergence angle of the incident beam light (diffusion laser beam light LB3). For example, the relationship between the magnification and the diffusion angle by the beam expanding optical system 13 (telescope) is as shown in FIG. That is, if the magnification becomes n times, the diffusion angle becomes 1 / n. Therefore, by selecting the optical characteristics of the first convex lens 131 and the second convex lens 132 constituting the beam expanding optical system 13 (telescope), the diffusion angle of the output laser beam light LB4 can be adjusted by the diffusion plate 121 (diffusion optical system). Further adjustment can be made based on the diffusion angle of the diffused laser beam light LB3 adjusted by 12).

  The light energy stabilizing device 11 that stabilizes the energy of the laser beam light LB1 from the solid-state UV pulse laser 10 and causes the laser beam light LB2 to enter the above-described diffusion optical system 12 is configured as shown in FIG. .

  In FIG. 5, a light energy stabilizing device 11 includes a beam splitter 111 (beam splitter) that splits a pulsed laser beam LB1 from the solid-state UV pulse laser 10 into a first beam L1 and a second beam L2. And a delay optical system 112, a variable optical attenuation optical system 113, an energy detector 114, a comparison circuit 115, and an AOE drive circuit 116. The delay optical system 112 delays the first light beam L1 from the beam splitter 111 by a predetermined time. The energy detector 114 detects the energy value of the second light beam L2 from the beam splitter 111 at a high speed (for example, response speed: 1 nanosecond) and outputs a detected voltage value corresponding to the energy value.

  The variable light attenuation optical system 113 on which the first light beam L1 having passed through the delay optical system 112 is incident is configured as shown in FIG.

  In FIG. 6, the variable optical attenuation optical system 113 has a first high-speed optical switch element 1131 (AOE1), a second high-speed optical switch element 1132 (AOE2), and a third high-speed optical switch element 1133 (AOE3). Each of the high-speed optical switch elements 1131, 1132, and 1133 is formed of, for example, an acousto-optic element (AOE), and is turned off when an L-level drive signal (acoustic signal) is applied, and switches the incident light beam. While the light is emitted as it is as the 0th-order diffracted light beam, it is turned on when an H-level drive signal is applied, and, for example, 15% of the incident light beam is emitted as it is as the 0th-order diffracted light beam. For example, 85% of the light beam is emitted as a first-order diffracted light beam.

  A prism 1134a is arranged behind the first high-speed optical switch element 1131 (AOE1), and two prisms 1134b and 1134c are arranged so as to sandwich the prism 1134a. The prism 1134a guides the first-order diffracted beam light from the first high-speed optical switch element 1131 (AOE1) to the prism 1134b, and guides the zero-order diffracted beam light from the first high-speed optical switch element 1131 (AOE1) to the prism 1134c. . The prism 1134b further guides the light beam guided from the prism 1134a to the second high-speed optical switch element 1132 (AOE2). The prism 1134c further guides the light beam guided from the prism 1134a to the third high-speed optical switch element 1133 (AOE3).

  A prism 1135a is arranged behind the second high-speed optical switch element 1132 (AOE2), and two prisms 1135b and 1135c are arranged so as to sandwich the prism 1135a. The prism 1135a guides the first-order diffracted beam light from the second high-speed optical switch element 1132 (AOE2) to the prism 1135b, while the zero-order diffracted beam light from the second high-speed optical switch element 1132 (AOE2) is transmitted to the prism 1135c. Lead. Further, a prism 1136a is arranged behind the third high-speed optical switch element 1133 (AOE3), and two prisms 1136b and 1136c are arranged so as to sandwich the prism 1136a. The prism 1136a guides the first-order diffracted light beam from the third high-speed optical switch element 1133 (AOE3) to the prism 1136b, and guides the zero-order diffracted light beam from the third high-speed optical switch element 1133 (AOE3) to the prism 1136c. .

  The variable light attenuation optical system 113 further has a first prism attenuator 1137a, a second prism attenuator 1137b, a third prism attenuator 1137c, and a fourth prism attenuator 1137d. The first prism attenuator 1137a has a transmittance T1, the second prism attenuator 1137b has a transmittance T2 (> T1), the third prism attenuator 1137c has a transmittance T3 (> T2), and the fourth prism attenuator 1137d has a transmittance T4. (> T3). That is, the attenuation rate of the first prism attenuator 1137a having the smallest transmittance T1 is the largest, and the attenuation rate of the second prism attenuator 1137b having the transmittance T2 and the attenuation rate of the third prism attenuator 1137b having the transmittance T3 are sequentially reduced. , The attenuation rate of the fourth prism attenuator 1137d having the largest transmittance T4 is the smallest.

  The first-order diffracted beam light from the second high-speed optical switch element 1132 (AOE2) guided to the prism 1135b by the prism 1135a is guided to the first prism attenuator 1137a by the prism 1135b. The light beam (energy E01) attenuated through the first prism attenuator 1137a enters the mixer 1138. Further, the 0th-order diffracted light beam from the second high-speed optical switch element 1132 (AOE2) guided to the prism 1135c by the prism 1135a is guided to the second prism attenuator 1137b by the prism 1135c. The light beam (energy E02) attenuated through the second prism attenuator 1137b enters the mixer 1138.

  The first-order diffracted light beam from the third high-speed optical switch element 1133 (AOE3) guided to the prism 1136b by the prism 1136a is guided to the third prism attenuator 1137a by the prism 1136b. The light beam (energy E03) attenuated through the third prism attenuator 1137c enters the mixer 1138. The 0th-order diffracted light beam from the third high-speed optical switch element 1133 (AOE3) guided to the prism 1136c by the prism 1136a is guided to the fourth prism attenuator 1137d by the prism 1136c. The light beam (energy E04) attenuated through the fourth prism attenuator 1137a enters the mixer 1138. Then, the mixer 1138 mixes one or a plurality of incident light beams, and outputs a laser beam light having an energy value Eo of the total energy value of the incident light beams to the output laser beam of the light energy stabilizing device 11. It is emitted as a light beam LB2.

  In the variable light attenuating optical system 113 having the above-described configuration, the three high-speed optical switch elements 1131, 1132, and 1133 are controlled to be switched to either the ON state or the OFF state, so that the incident first beam light L1 is controlled. The substantial attenuation rate (transmittance) can be changed. Then, the variable light attenuation optical system 113 can emit the emission beam LB2 having an energy value according to the attenuation rate.

  Returning to FIG. 5, the delay optical system 112 converts the first light beam L1 into the operation characteristics of the variable optical attenuation optical system 113, for example, the operation characteristics (response time) of each of the high-speed optical switch elements 1131, 1132, and 1133 (AOE). ). For example, as shown in FIG. 7, when the response time (time from to to t1) of each of the high-speed optical switches 1131, 1132, and 1133 (AOE) in the variable optical attenuation optical system 113 is, for example, 100 nanoseconds, The time for delaying the pulse of the first light beam L1 (delay time) is set to a time longer than the response time (time from to to t2), for example, about 160 nanoseconds. Thereby, the pulse itself of the first light beam L1 whose energy is actually detected can pass through each of the high-speed optical switches 1131, 1132, and 1133 (AOE) driven based on the energy value. The delay optical system 112 includes an optical path having a length corresponding to the delay time. For example, a 167 nanosecond delay can be obtained with a 50 meter optical path.

  Returning to FIG. 5, the comparison circuit 115, the AOE drive circuit 116, and the above-mentioned variable optical attenuation optical system 113 use the delay optical system based on the energy value of the second light beam L 2 detected by the energy detector 114. A stabilizer for stabilizing the energy of the first light beam L1 from the system 112 is configured. In this stabilizer, the comparison circuit 115 and the AOE drive circuit 116 are controllers, and as the energy value of the second light beam L2 detected by the energy detector 114 increases, the variable optical attenuation optical system Control is performed to increase the substantial attenuation rate at 113.

  The comparison circuit 115 has three comparators (flash comparators) 115a, 115b, and 115c. In the comparators 115a, 115b, and 115c, the detection voltage values corresponding to the energy value of the second light beam L2 from the energy detector 114 are larger than the corresponding reference voltage values Ref1, Ref2, and Ref3 (Ref1> Ref2> Ref3). And outputs a comparison determination signal indicating whether or not this is the case. The energy value Ei (V) of the second light beam L2 corresponding to the detected voltage value V from the energy detector 114 is determined by the three comparison determination signals from the three comparators 115a, 115b, and 115c (comparing circuit 115). Ei (V)> E (Ref1), E (Ref1) ≧ Ei (V)> E (Ref2), E (Ref2) ≧ Ei (V)> E (Ref3), Ei (V) ≦ E (Ref3).

  The AOE drive circuit 116 has three drive signals 1 in a state (H level or L level) according to the energy values of the four stages of the second light beam L2 represented by the three comparison determination signals from the comparison circuit 115. 2, 3 are output. Specifically, when the three comparison determination signals indicate a stage where the energy value E (V) of the second light beam L2 is the highest (Ei (V)> E (Ref1)), the two drive signals 1, 2 Is set to the H level, and the remaining one drive signal 3 is set to the L level. When the three comparison determination signals indicate a stage where the energy value E (V) of the second light beam L2 is the second highest (E (Ref1) ≧ Ei (V)> E (Ref2)), the drive signal 1 is set to H. Level, and the remaining two drive signals 2 and 3 are set to L level. If the three comparison determination signals indicate a stage where the energy value E (V) of the second light beam L2 is the third highest (E (Ref2) ≧ Ei (V)> E (Ref3)), the drive signal 3 is set to H. Level, and the remaining two drive signals 1 and 2 are set to L level. In addition, when the three comparison determination signals indicate a stage where the energy value E (V) of the second light beam L2 is the lowest (Ei (V) ≦ E (Ref1)), all the drive signals 1, 2, and 3 are used. Set to L level.

  The three drive signals 1, 2, and 3 output from the AOE drive circuit 116 are output to the first high-speed optical switch 1131 (AOE1), the second high-speed optical switch 1132 (AOE2), and the third high-speed optical switch 113 in the variable optical attenuation optical system 113. The signal is supplied to the variable optical attenuation optical system 113 as a signal for switching the optical switch 1133 (AOE3) (see FIG. 6). Specifically, the drive signal 1 is applied to the first high-speed optical switch element 1131 (AOE1), the drive signal 2 is applied to the second high-speed optical switch element 1132 (AOE2), and the drive signal 3 is applied to the third high-speed optical switch element 1133 (AOE3). ) Respectively.

  In the light energy stabilizing device 11 described above, the high-speed optical switching element 1131 for the energy values Ei1, Ei2, Ei3, and Ei4 (Ei1> Ei2> Ei3> Ei4) of the second light beam L1 (incident light) detected by the energy detector 114. FIG. 8 shows the relationship between the driving states (on state, off state) of (AOE1), 1132 (AOE2), and 1133 (AOE3) and the energy of the outgoing laser beam light LB2 (outgoing light). In FIG. 8, the energy value Ei1 is the largest energy value, Ei1> E (Ref1), and the energy value Ei2 is the second largest energy value, E (Ref1) ≧ Ei2> E ( Ref2). The energy value Ei3 is the third largest energy value, E (Ref2) ≧ Ei3> E (Ref3), and the energy value Ei4 is the smallest energy value, Ei4 ≦ E (Ref3). It is.

In the case of the detected energy value Ei1, the drive signals 1 and 2 from the AOE drive circuit 116 go to H level, and the remaining drive signals 3 go to L level. As a result, the first high-speed optical switch element 1131 (AOE1) and the second high-speed optical switch element 1132 (AOE2) are turned on (ON), and the third high-speed optical switch element 1133 (AOE3) is turned off (OFF). Be in a state. In this case, each of the first high-speed optical switch element 1131 (AOE1) and the second high-speed optical switch element 1132 (AOE2) emits 85% of the first-order diffracted light beam and 15% of the 0th-order diffracted light beam. From the third high-speed optical switch element 1133 (AOE3), 100% of the 0th-order diffracted beam light is emitted. As a result, the incident light beam (the first light beam L1) having the energy value Ei1 passes through the first prism attenuator 1137a (the transmittance T1) and the light beam (Eo1) passing through the second prism attenuator 1137b (the transmittance T2). The light beam (Eo2) is split into a light beam (Eo4) passing through the fourth prism attenuator 1137d (transmittance T4) and is incident on the mixer 1138. The three light beams are mixed by the mixer 1138, and the output laser beam light LB2 having the energy value Eo is emitted from the mixer 1138. The energy value Eo of the emitted laser beam light LB2 is the sum of the energies Eo1, Eo2, and Eo4 of the three light beams,
^{Eo = Ei1 × (0.85 2 ×} T1 + 0.85 × 0.15 × T2 + 0.15 × T3) ··· (1)
Becomes

In the case of the detected energy value Ei2, the drive signal 1 from the AOE drive circuit 116 goes high, and the remaining two drive signals 2, 3 go low. As a result, the first high-speed optical switch element 1131 (AOE1) is turned on (ON), and the two second high-speed optical switch elements 1132 (AOE2) and the third high-speed optical switch element 1133 (AOE3) are turned off ( OFF). In this case, the first high-speed optical switch element 1131 (AOE1) emits 85% of the first-order diffracted light beam and 15% of the 0th-order diffracted light beam, and outputs the second high-speed optical switch element 1132 (AOE2) and the third. From each of the high-speed optical switch elements 1133 (AOE3), 100% 0th-order diffracted beam light is emitted. As a result, the incident light beam (the first light beam L1) having the energy value Ei2 passes through the light beam (Eo2) passing through the second prism attenuator 1137b (transmittance T2) and the light beam (Eo2) passing through the fourth prism attenuator 1137d (transmittance T4). The light is split into a light beam (Eo4) and incident on the mixer 1138. The two light beams are mixed by the mixer 1138, and the output laser beam light LB2 having the energy value Eo is emitted from the mixer 1138. The energy value Eo of the emitted laser beam light LB2 is the sum of the energy values Eo2 and Eo4 of the two light beams,
Eo = Ei2 × (0.85 × T2 + 0.15 × T4) (2)
Becomes

In the case of the detected energy value Ei3, the drive signals 1 and 2 from the AOE drive circuit 116 are at L level, and the remaining drive signals 3 are at H level. As a result, the first high-speed optical switch element 1131 (AOE1) and the second high-speed optical switch element (AOE2) are turned off (OFF), and the third high-speed optical switch element 1133 (AOE3) is turned on (ON). Become. In this case, 100% 0th-order diffracted beam light is emitted from the first high-speed optical switch element 1131 (AOE1), and light beam is emitted from the second high-speed optical switch element 1132 (AOE2) having no incident light. In addition, 85% of the first-order diffracted light beam and 15% of the 0th-order diffracted light beam are emitted from the third high-speed optical switch element 1133 (AOE3). As a result, the incident light beam (the first light beam L1) having the energy value Ei3 is a light beam that passes through the third prism attenuator 1137c (transmittance T3) and a light beam that passes through the fourth prism attenuator 1137d (transmittance T4). And enters the mixer 1138. The two light beams are mixed by the mixer 1138, and the output laser beam light LB2 having the energy value Eo is emitted from the mixer 1138. The energy value Eo of the emitted laser beam light LB2 is the sum of the energy values Eo3 and Eo4 of the two light beams,
Eo = Ei3 × (0.85 × T3 + 0.15 × T4) (3)
Becomes

In the case of the detected energy value Ei4, all of the three drive signals 1, 2, and 3 from the AOE drive circuit 116 are at the L level. Thereby, each of the first high-speed optical switch element 1131 (AOE1), the second high-speed optical switch 1132 (AOE2), and the third high-speed optical switch 1133 (AOE3) is turned off. In this case, 100% 0th-order diffracted beam light is emitted from the first high-speed optical switch 1131 (AOE1), and beam light is emitted from the second high-speed optical switch element 1132 (AOE2) having no incident light. The 100% 0th-order diffracted light beam is also emitted from the third high-speed optical switch element 1133 (AOE3). As a result, the incident light beam (the first light beam L1) having the energy value Ei4 enters the mixer 1138 through the fourth prism attenuator 1137d (transmittance T4). From the mixer 1138, the light beam passes through the fourth prism attenuator 1137d and is emitted as it is as an emission laser beam LB2 having an energy value Eo. The energy value Eo of the emitted laser beam light LB2 is the energy value Eo4 of the light beam that has passed through the fourth prism attenuator 1137d,
Eo = Ei4 × T4 (4)
Becomes

  In the light energy stabilizing device 11 as described above, the larger the detected energy value of the incident light beam (second light beam L2), the lower the transmittance of a larger amount of light beam (first light beam L1). (Higher attenuation) through the prism attenuator. Therefore, the fluctuation of the energy value is suppressed, and the laser beam light LB2 whose energy value is stabilized can be emitted.

For example, in the above-described example (see FIG. 8), the energy value of the incident laser beam (first light beam L1) that fluctuates is Ei1 = 104.
Ei2 = 102
Ei3 = 100
Ei4 = 98
(E (Ref1) = 103, E (Ref2) = 101, E (Ref3) = 99),
The attenuation rate of each prism attenuator 1137a, 1137b, 1137c, 1137d is T1 = 92%
T2 = 94%
T3 = 96%
T4 = 98%
Consider the energy value Eo of the emitted laser beam light in the case of

(1) In the case of Ei1 = 104 (Ei1> E (Ref1)) The energy value Eo of the emitted laser beam light LB2 calculated according to the equation (1) is:
^{Eo = 104 × (0.85 2 ×} 0.92 + 0.85 × 0.15 × 0.94 + 0.15 × 0.98) = 99.63
Becomes
(2) In the case of Ei2 = 102 (E (Ref1)> Ei2 ≧ E (Ref2)) The energy value Eo of the emitted laser beam light LB2 calculated according to the equation (2) is:
Eo = 102 × (0.85 × 0.94 + 0.15 × 0.98) = 96.49
Becomes
(3) When Ei3 = 100 (E (Ref2> Ei3 ≧ E (Ref3)) The energy value Eo of the output laser beam LB2 calculated according to the equation (3) is:
Eo = 100 × (0.85 × 0.96 + 0.15 × 0.98) = 96.3
Becomes
(4) When Ei4 = 98 (Ei4 ≦ E (Ref3)) The energy value Eo of the emitted laser beam LB2 calculated according to the equation (4) is:
Eo = 98 × 0.98 = 96.04
Becomes

  According to the above consideration, the energy value Ei of the incident laser beam light (first beam light L1) is 101 ± 3 (104 to 98) and the variation rate is about 3%, The energy value Eo of the light L2 is 97.8 ± 1.8 (99.6 to 96.0), and its fluctuation rate is about 1.8%. Thus, the fluctuation of the energy value is suppressed, and the laser beam light LB2 whose energy value is stabilized is emitted.

  As described above, the laser beam light LB2 whose energy is stabilized and emitted from the light energy stabilizing device 11 becomes the diffused laser beam light LB3 via the diffusion optical system 12 (diffusion plate 121) as described above. Further, the diffused laser beam light LB3 passes through the beam expanding optical system 13 to be emitted laser beam light LB4 and is emitted from the light source device 100 (see FIGS. 1 to 3).

  According to such a light source device 100, the laser beam light LB1 from the solid-state UV pulse laser 10 as a laser light source allows the light energy stabilizing device 11 to suppress temporal fluctuation of energy and stabilize energy. Since the coherence is reduced by the diffusion optical system 12 (diffusion plate 121), the coherence is improved, so that the energy stability is excellent, and the coherence is reduced without the electric field intensity reaching the intensity limit at the focal point. The emitted laser beam light (emitted laser beam light) can be emitted.

  As described above, together with the light source device 100 that emits the laser beam light LB4, the long-axis homogenizer 14, the short-axis homogenizer 15, and the short-axis reduction projection lens system 16, which constitute the line beam homogenizer (see FIG. 1), It is configured as follows.

  First, the long axis homogenizer 14 is configured as shown in FIG.

  9, a long axis homogenizer 14 has a plurality of cylindrical lenses (each cylindrical lens extends in a short axis direction DM orthogonal to the long axis direction DL) arranged in a long axis direction DL (a direction parallel to the paper surface). ), A first long-axis lens array 141a and a second long-axis lens array 141b, and a long-axis condenser lens 142 arranged adjacent to the second long-axis lens array 141b. The laser beam light LB4 from the light source device 100 incident on the first long-axis lens array 141a is split and diffused by the corresponding pair of cylindrical lenses of the first long-axis lens array 141a and the second long-axis lens array 141b. The split diffused laser beam is enlarged and projected on the long axis projection surface S2 so as to be enlarged in the long axis direction DL through the long axis condenser lens 142. Then, on the long axis projection surface S2, the plurality of divided diffused laser beam lights from each pair of cylindrical lenses are multiplexed to form a beam spot of a predetermined length (for example, about 50 mm) extending in the long axis direction DL. . In this manner, a plurality of divided diffused laser beam lights are multiplexed on the long axis projection plane S2, so that an energy distribution (intensity distribution) in the long axis direction DL of a beam spot formed on the long axis projection plane S2. However, for example, as shown in FIG.

  Next, the short axis homogenizer 15 is configured as shown in FIG.

  In FIG. 11, the short-axis homogenizer 15 includes a plurality of cylindrical lenses (each cylindrical lens is arranged in the short-axis direction DM) arranged in a short-axis direction DM (a direction parallel to the paper surface) orthogonal to the long-axis direction DL. A first short-axis lens array 151a, a second short-axis lens array 152b, and a short-axis condenser lens 152 disposed adjacent to the second short-axis lens array 151b. It has. The short-axis homogenizer 15 is arranged with respect to the long-axis homogenizer 14 such that the laser beam light incident surface of the first short-axis lens array 151a matches the long-axis projection surface S2 (see FIG. 5). Have been. Thereby, the laser beam light LB5 from the long axis homogenizer 14 is applied so that the beam spot extending in the long axis direction DL is projected onto the surface of the first short axis lens array 151a as the long axis projection plane S2. The light enters the first short-axis lens array 151a. As described above, the laser beam light LB5 incident on the first short-axis lens array 151a is split (slightly diffused) by the corresponding pair of cylindrical lenses of the first short-axis lens array 151a and the second short-axis lens array 151b. The divided laser beam LB6 is projected on the short-axis projection surface S3 by the short-axis condenser lens 152. Then, on the short axis projection surface S3, a plurality of divided laser beam lights from each pair of cylindrical lenses are multiplexed to form a beam spot. As described above, by multiplexing the plurality of divided laser beam lights LB6 on the short-axis projection surface S3, the energy distribution (intensity distribution) of the beam spot formed on the short-axis projection surface S3 in the short-axis direction DM. Is made uniform.

  The short-axis reduction projection lens system 16 arranged downstream of the short-axis homogenizer 15 is configured as shown in FIG.

  12, the short axis reduction projection lens system 15 includes two cylindrical plano-convex lenses 161 and 162. As described above, the plurality of split laser beam lights from the short-axis homogenizer 15 are multiplexed on the short-axis projection surface S3, and further, the laser beam light LB6 diverging from the short-axis projection surface S3 is divided into two cylindrical plano-convex lenses 161, By 162, the light is condensed on the focal projection plane S4 and reduced in the short-axis direction DM (for example, 0.5 mm in width). In the beam spot formed by being reduced in the short-axis direction DM on the focal projection plane S4, the laser beam LB6 formed by multiplexing the plurality of divided laser beam lights from the short-axis homogenizer 15 on the short-axis projection plane S3. Is maintained in the short-axis direction DM.

  As described above, the long axis homogenizer 14, the short axis homogenizer 15, and the short axis reduction projection lens system 16 form a linear spot (for example, 50 mm × 0.5 mm) extending in the long axis direction DM on the focal projection plane S4. The obtained linear laser beam LB7 is obtained as a laser beam emitted from the line beam homogenizer.

  The line beam homogenizer as described above can be used, for example, in an annealing process for a semiconductor substrate. In that case, the semiconductor substrate is arranged so that the processing surface coincides with the focal projection surface S4 (see FIG. 12), and the processing surface is irradiated with the linear laser beam LB7 emitted from the line beam homogenizer. In this state, the processing surface of the semiconductor substrate is scanned by the linear laser beam light by relatively moving the semiconductor substrate and the line beam homogenizer in the short axis direction DM. In this manner, the processing surface is annealed by the thermal energy of the linear laser beam LB7 that scans the processing surface of the semiconductor substrate in the short-axis direction DM.

  According to the line beam homogenizer as described above, the energy stability is excellent, and the electric field intensity at the focal point does not reach the intensity limit. A linear laser beam light having a uniform energy distribution in both axial directions is formed. Thereby, more stable linear laser beam light can be obtained. Therefore, if such a line beam homogenizer is applied to the annealing of the surface of a semiconductor substrate, the surface of the semiconductor substrate can be more accurately and uniformly annealed.

  The light source device 100 described above can be applied to an optical device other than the line beam homogenizer. In this case, also in the other optical device, it is possible to use laser beam light having excellent energy stability and having reduced coherence without the electric field intensity at the focal point reaching the intensity limit.

  In the light source device 100 described above, the light energy stabilizing device 11 can be omitted depending on the required performance of energy stability in the optical device to be used. Further, in the case of using in an optical device in which energy stability is an important required performance, at least the diffusion optical system 12 among the diffusion optical system 12 and the beam expansion optical system 13 (emission optical system) can be omitted.

  Further, in the light source device 100 described above, the laser light source is not limited to the solid-state UV pulse laser 10 depending on the optical device to which the light source device 100 is applied. Can be used.

  Instead of the beam expanding optical system 13 as the output optical system, another type of output optical system such as a collimator or another optical system related to beam shaping can be used.

  Note that the present invention is not limited to the above-described embodiment and its modifications. Various modifications can be made based on the spirit of the present invention, and these are not excluded from the scope of the present invention.

10. Solid-state UV pulse laser (laser light source)
11 Light Energy Stabilizer 12 Diffusion Optical System 13 Beam Expansion Optical System (Emission Optical System)
DESCRIPTION OF SYMBOLS 14 Long axis homogenizer 15 Short axis homogenizer 16 Short axis reduction lens system 100 Light source device 111 Beam splitter 112 Delay optical system 113 Variable light attenuation optical system 114 Energy detector 115 Comparison circuit 115a, 115b, 115c Comparator 116 AOE drive circuit 121 Diffusion plate 131 First convex lens 132 Second convex lens 141a First long axis lens array 141b Second long axis lens array 142 Long axis condenser lens 151a First short axis lens array 151b Second short axis lens array 152 Short axis condenser lens 161 , 162 Cylindrical plano-convex lens 1131 First high-speed optical switch element (AOE1)
1132 Second high-speed optical switch element (AOE2)
1133 Third high speed optical switch element (AOE3)
1134a, 1134b, 1134c, 1135a, 1135b, 1135c,
1136a, 1136b, 1136c Prism 1137a First prism attenuator 1137b Second preism attenuator 1137c Third prism attenuator 1137d Fourth prism attenuator

Claims (10)

A light source device having a laser light source that emits a laser beam light,
A diffusion optical system that converts the laser beam light from the laser light source into a diffused laser beam light having a predetermined diffusion angle,
An emission optical system that converts the diffused laser beam from the diffusion optical system into an emitted laser beam from the light source device and emits the emitted laser beam.   The diffusion angle of the diffused laser beam light is larger than the diffusion angle of the laser beam light emitted from the laser light source, and all of the diffused laser beam light from the diffusion optical system can enter the emission optical system. The light source device according to claim 1, wherein the light source device has a maximum diffusion angle or less.   3. The light source device according to claim 2, wherein the divergence angle of the divergent laser beam light is within a range of 10 ± 5 milliradians. The output optical system includes:
The light source according to any one of claims 1 to 3, further comprising a beam expanding optical system that expands the diameter of the diffused laser beam from the diffusion optical system and emits the laser beam having the expanded diameter. apparatus. A light energy stabilizing device that stabilizes energy by suppressing temporal fluctuation of the energy of the laser beam light from the laser light source,
The light source device according to claim 1, wherein the laser beam light having passed through the light energy stabilizing device is incident on the diffusion optical system. The light energy stabilizer,
A beam splitter that splits the laser beam from the laser light source into a first beam and a second beam;
A delay optical system for delaying the first light beam obtained by the beam splitter;
An energy detector that detects an energy value of the second light beam obtained by the beam splitter;
A stabilizer for stabilizing the energy of the first light beam from the delay optical system based on the energy value of the second light beam detected by the energy detector,
The light source device according to claim 5, wherein the first light beam whose energy is stabilized by the stabilizer is incident on the diffusion optical system. The stabilizer has a variable attenuation factor, and a variable light attenuation optical system through which the first light beam from the delay optical system passes;
7. The light source device according to claim 6, further comprising: a controller configured to increase an attenuation rate in the variable light attenuation optical system as an energy value detected by the energy detector increases. A light source device including a laser light source that emits a laser beam light,
A beam splitter for splitting a laser beam from the laser light source into a first beam and a second beam;
A delay optical system for delaying the first light beam obtained by the beam splitter;
An energy detector that detects an energy value of the second light beam obtained by the beam splitter;
A stabilizer for stabilizing the energy of the first light beam from the delay optical system based on the energy value of the second light beam detected by the energy detector,
A light source device that emits the first light beam whose energy is stabilized by the stabilizer. The stabilizer has a variable attenuation factor, and a variable light attenuation optical system through which the first light beam from the delay optical system passes;
The light source device according to claim 8, further comprising: a controller configured to increase an attenuation rate in the variable light attenuation optical system as an energy value detected by the energy detector increases. A light source device according to any one of claims 1 to 9,
Generating a linear laser beam extending in the long axis direction in which the energy distribution in both the long axis direction and the short axis direction orthogonal to the long axis direction is made uniform from the laser beam emitted from the light source device; And a homogenizing optical system.

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