JP7265743B2 - Light source device and line beam homogenizer using it - Google Patents

Description

The present invention relates to a light source device having 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. This laser annealing apparatus uses a light source device that includes a laser light source (for example, a solid-state laser) that emits laser beam light and a beam expander that expands the diameter of the laser beam light from the laser light source. Then, from such a light source device and a laser beam light having a predetermined spot size emitted from the light source device, the energy distribution is made uniform in both the major axis direction and the minor axis direction orthogonal to the major axis direction. , and a homogenizing optical system (a long-axis homogenizer and a short-axis homogenizer) for generating the linear laser beam light extending in the long-axis direction constitute a line beam homogenizer.

In a laser annealing apparatus equipped with a line beam homogenizer as described above, a linear laser beam formed by the homogenizing optical system scans the surface of the amorphous semiconductor film in the minor axis direction. The surface of the amorphous semiconductor film is annealed by the thermal energy of the linear laser beam light that scans the surface of the amorphous semiconductor film in the minor 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 coherence of the laser beam light emitted from the laser light source is high. Annealing treatment can be effectively performed by utilizing the high energy of such a highly coherent laser beam.

On the other hand, laser beam light with such high coherence has high convergence. For this reason, for example, when the laser beam light is focused at one point by an optical system arranged after the laser light source, for example, a spherical convex lens of a telescope included in the beam expander, the electric field intensity at the focus point is reaches the intensity limit (breakdown), and a phenomenon can occur in which the laser beam does not travel any further.

Further, in the homogenization optical system, for example, the laser beam light is dispersed by each lens of the lens array, and by superimposing the dispersed laser beam light, the energy distribution of the formed linear laser beam light is homogenized. (Distributed homogenizer). When a laser beam light with extremely high coherence is incident on such a homogenization optical system, interference fringes may occur, and the uniformity of the energy distribution of the formed linear laser beam light 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 light with high coherence to prevent the electric field strength at the condensing point from reaching the strength limit, thereby improving coherence. A light source device capable of emitting a relaxed laser beam is provided.

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 laser beam light, and a diffusion optical system that converts the laser beam light from the laser light source into a diffuse laser beam light having a predetermined diffusion angle. and an output optical system for outputting the diffused laser beam light from the diffusion optical system as output laser beam light for use in another optical device from the light source device, the output optical system comprising: A beam enlarging optical system is included for enlarging the light diameter of the diffused laser beam light from the diffusion optical system and emitting the laser beam light with the expanded light diameter.

According to such a configuration, the coherence of the laser beam light from the laser light source is relaxed by the diffusion optical system, and the diffused laser beam light has a predetermined diffusion angle. Then, the diffused laser beam light with reduced coherence from the diffusion optical system is emitted as the emitted laser beam light through the emission optical system. Furthermore, in the emission optical system, when the diffused laser beam light from the diffusion optical system is incident on the beam expansion optical system, the beam expansion optical system expands the light diameter of the diffused laser beam, A laser beam light having a diameter of 0.5 mm is emitted from the beam expanding optical system. The light diameter of the emitted light beam is enlarged from the light diameter of the incident light beam (diffused laser beam light). can be changed (reduced) from

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 It can be less than or equal to the maximum diffusion angle that can be incident on the output optical system, and more specifically, it can be a value within the range of 10±5 milliradians.

The light source device according to the present invention has a light energy stabilizing device that suppresses temporal fluctuations in the energy of the laser beam light from the laser light source to stabilize the energy, and the laser beam that has passed through the light energy stabilizing device. It can be configured such that light is 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 this light source device can be stabilized.

In the light source device according to the present invention, the light energy stabilizing device includes a beam splitter that splits the laser beam light from the laser light source into a first light beam and a second light beam, and 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. a stabilizer that stabilizes the energy of the first light beam from the delay optical system based on the energy value of the first light beam whose energy is stabilized by the stabilizer. It can be configured to be incident on the diffusion optical system.

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

A light delay characteristic (eg, delay time) in the delay optical system can be determined based on at least the temporal operating 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. The configuration can be such that the controller increases the attenuation rate in the variable light attenuation optical system as the energy value to be applied increases.

According to such a configuration, the first light beam from the delay optical system is attenuated by the variable light attenuation 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 that forms the laser beam light from the laser light source together with the second light beam.

A light source device according to the present invention includes a laser light source that emits laser beam light, and a beam splitter that splits the laser beam light from the laser light source into a first light beam and a second light beam. a delay optical system for delaying the first light beam obtained by the beam splitter; an energy detector for detecting the energy value of the second light beam obtained by the beam splitter; a stabilizer that stabilizes 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 beam light thus obtained is emitted.

According to such a configuration, the laser beam light from the laser light source is split into the first beam light and the second beam light by the beam splitter, the first beam light enters the delay optical system, and the second beam light An energy value of the light is detected by an energy detector. The first light beam that has passed through the delay optical system is stabilized by suppressing temporal changes in its energy based on the energy value of the second light beam detected by the energy detector. . The first light beam whose energy has been stabilized is emitted as 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. and a controller that increases the attenuation rate in the variable light attenuation optical system as the energy value to be applied increases.

Further, the line beam homogenizer according to the present invention includes any one of the light source devices described above, and a laser beam emitted from the light source device in both the major axis direction and the minor axis direction orthogonal to the major axis direction. and a homogenizing optical system for generating a linear laser beam light extending in the major axis direction and having a uniform energy distribution at.

According to such a configuration, the energy distribution in both the long-axis direction and the short-axis direction from the laser beam light (output laser beam light) from the light source device whose coherence is relaxed by the diffusion optical system is homogenized. to generate a linear laser beam light extending in the long axis direction.

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

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

FIG. 1 is a block diagram showing the 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. 3 is a diagram showing an enlarging optical system included in the light source device in the line beam homogenizer shown in FIG. 1. FIG. FIG. 4 is a diagram showing the relationship between the magnification (magnification factor) and the diffusion angle of the magnifying optical system (exiting optical system) shown in FIG. 5 is a diagram showing the configuration of a light energy stabilizing device included in the light source device in the line beam homogenizer shown in FIG. 1. FIG. 6 is a diagram showing the configuration of a variable light attenuation optical system in the optical energy stabilization device shown in FIG. 5. FIG. FIG. 7 is a timing chart showing temporal operating characteristics of the variable light attenuation optical system (high-speed optical switching element (AOE)) shown in FIG. 6 in relation to the detection timing of the first pulsed laser beam. . 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 the basic configuration of the 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 the basic configuration of a short-axis homogenizer. FIG. 12 is a diagram showing the configuration of a short-axis reduction projection lens system.

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

A line beam homogenizer according to an embodiment of the present invention is constructed as shown in FIG. In FIG. 1, this line beam homogenizer comprises 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 homogenizes the energy distribution of the emitted laser beam light LB4 from the light source device 100 in the long-axis direction. The short-axis homogenizer 15 homogenizes the energy distribution in the short-axis direction orthogonal to the long-axis direction of the laser beam light LB5 that has passed through the long-axis homogenizer 14 . The short-axis reduction projection lens system 16 reduces the spot size of the laser beam light LB6 that has passed through the short-axis homogenizer 15 in the short-axis direction. In this way, the emitted laser beam light LB4 from the light source device 100 passes through the long-axis homogenizer 14, the short-axis homogenizer 15 (homogenizing optical system), and the short-axis reduction projection lens system 16. A linear laser beam light LB7 extending in the long axis direction with uniform energy distribution in both the short axis direction and the short axis direction is generated.

The light source device 100 includes a solid-state UV pulse laser 10 as a laser light source, a light energy stabilizer 11, a diffusion optical system 12, and a beam expansion optical system 13 (beam expander: emission optical system). there is The light energy stabilizing device 11 suppresses temporal fluctuations in the energy of the laser beam light LB1 having a frequency in the UV band (ultraviolet band) emitted in a pulse form from a solid-state UV pulse laser 10 (laser light source), thereby reducing the energy. A stabilized laser beam light LB2 is emitted. The diffusion optical system 12 diffuses the laser beam light LB2 that has passed through the optical energy stabilizer 11 into a diffused laser beam LB3 having a predetermined diffusion angle. The beam expansion optical system 13 (output optical system) converts the laser beam light having a diameter larger than that of the diffused laser beam light LB3 incident from the diffusion optical system 11 to the emitted laser beam light LB4 of the light source device 100. , enter a long-axis homogenizer 14 (homogenizing optical system).

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

A specific configuration of the optical energy stabilizing device 11 that stabilizes 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 is composed of a diffusion plate 121, as shown in FIG. The diffuser plate 121 has, for example, a structure in which a fine uneven pattern (holographic pattern) is formed on the surface of a transparent substrate made of resin such as epoxy resin. The laser beam light LB2 from the light energy stabilizing device 11 that is incident with a beam diameter Φ1 is diffused by the diffusion plate 121, and diffused laser light with a beam diameter Φ2 (≧Φ1) is projected onto the incident surface S1 of the beam expanding optical system 13. It enters as beam light LB3.

The diffusion angle of the diffused laser beam light LB3 is larger than the diffusion angle of the laser beam light LB2 emitted from the light energy stabilizer 11, that is, the diffusion angle of the laser beam light LB1 from the solid-state UV pulse laser 10 (for example, 0.26 degrees (4.5 milliradians)), and all of the diffused laser beam light LB3 from the diffusion plate 121 is less than the maximum diffusion angle at which the incident surface S1 of the beam expansion optical system 13 can be incident. Specifically, the diffusion angle is preferably set to a value within the range of 10±5 milliradians from the viewpoint of suppressing coherence without greatly impairing the energy concentration of the laser beam light. For example, when the diffusion angle θ=0.5 degrees (approximately 9 milliradians), the laser beam light LB2 incident on the diffuser plate 121 with a beam diameter Φ1=6 mm is separated from the diffuser plate 121 by 45 centimeters (L=45 cm). The diffused laser beam light LB3 with a beam diameter Φ2≈10 mm is incident on the incident surface S1 of the beam expansion optical system 13 .

Next, as shown in FIG. 3, the beam expansion optical system 13 (beam expander: output optical system) includes two convex lenses, a first convex lens 131, which are arranged in series in the optical axis direction and which are parallel to each other. and a second convex lens 132. The diffused laser beam light LB3 from the diffusion plate 121 described above is incident on the first convex lens 131 (incidence surface S1 of the beam expansion optical system 13) and condensed at the condensing point P (focus). Then, the laser beam light diverging from this converging point P is incident on the second convex lens 132 and emitted from the second convex lens 132 as a laser beam LB4 (outgoing laser beam light).

The optical diameter of the incident diffused laser beam light LB3 on the incident surface S1 is enlarged by the enlarging function based on the optical characteristics (focal length, etc.) of the first convex lens 131 and the second convex lens 132 that constitute the telescope. , the laser beam light with the enlarged diameter is emitted from the beam expansion optical system 13 as the emitted laser beam light LB4 from the light source device 100. FIG. By increasing the diameter of the emitted light beam (laser beam light LB4) from the diameter of the incident light beam (diffused laser beam light LB3), as a result, the emitted light beam (laser beam light LB4) is diffused. The angle can be changed (reduced) from the divergence angle of the incident beam light (diffused laser beam light LB3). For example, the relationship between the magnification of the beam expansion optical system 13 (telescope) and the diffusion angle 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 that constitute the beam expansion optical system 13 (telescope), the diffusion angle of the emitted laser beam light LB4 can be adjusted to the diffusion plate 121 (diffusion optical system 12) can be further adjusted from the divergence angle of the diffused laser beam light LB3 adjusted by 12).

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

In FIG. 5, the light energy stabilizing device 11 includes a beam splitter 111 (beam splitter) that splits the pulsed laser beam light LB1 from the solid-state UV pulse laser 10 into a first light beam L1 and a second light beam L2. , and has a delay optical system 112 , a variable light attenuation optical system 113 , an energy detector 114 , a comparison circuit 115 and an AOE driving 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 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 into which the first light beam L1 that has passed through the delay optical system 112 is incident is configured as shown in FIG.

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

A prism 1134a is arranged behind the first high-speed optical switching element 1131 (AOE1), and two prisms 1134b and 1134c are arranged so as to sandwich the prism 1134a. The prism 1134a guides the 1st-order diffracted light beam from the first high-speed optical switching element 1131 (AOE1) to the prism 1134b, and guides the 0th-order diffracted light beam from the first high-speed optical switching element 1131 (AOE1) to the prism 1134c. . The prism 1134b further guides the beam light guided from the prism 1134a to the second high-speed optical switching element 1132 (AOE2). Also, the prism 1134c further guides the beam light guided from the prism 1134a to the third high-speed optical switching element 1133 (AOE3).

A prism 1135a is arranged behind the second high-speed optical switching element 1132 (AOE2), and two prisms 1135b and 1135c are arranged so as to sandwich the prism 1135a. The prism 1135a guides the 1st-order diffracted light beam from the second high-speed optical switching element 1132 (AOE2) to the prism 1135b, while directing the 0th-order diffracted light beam from the second high-speed optical switching element 1132 (AOE2) to the prism 1135c. lead. A prism 1136a is arranged behind the third high-speed optical switching element 1133 (AOE3), and two prisms 1136b and 1136c are arranged so as to sandwich the prism 1136a. The prism 1136a guides the 1st-order diffracted light beam from the third high-speed optical switching element 1133 (AOE3) to the prism 1136b, and guides the 0th-order diffracted light beam from the third high-speed optical switching 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), respectively. That is, the attenuation rate of the first prism attenuator 1137a with the smallest transmittance T1 is the largest, followed by the attenuation rate of the second prism attenuator 1137b with the transmittance T2 and the attenuation rate of the third prism attenuator 1137b with the transmittance T3. , the attenuation factor of the fourth prism attenuator 1137d with the largest transmittance T4 is the smallest.

The first-order diffracted light beam from the second high-speed optical switching 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. As shown in FIG. Also, the 0th-order diffracted beam light from the second high-speed optical switching 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. FIG.

Also, the 1st-order diffracted light beam from the third high-speed optical switching 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. FIG. Also, the 0th-order diffracted beam light from the third high-speed optical switching 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. FIG. Then, the mixer 1138 mixes one or more incident light beams to produce a laser beam light having an energy value Eo that is the sum of the energy values of the incident light beams, which is emitted from the light energy stabilizing device 11. It is emitted as beam light LB2.

In the variable light attenuation optical system 113 configured as described above, the three high-speed optical switch elements 1131, 1132, and 1133 are controlled to be switched between ON and OFF states, thereby controlling the incident first light beam L1. A substantial attenuation rate (transmittance) can be changed. Then, the variable light attenuation optical system 113 can emit an emitted beam LB2 having an energy value corresponding to the attenuation rate.

Returning to FIG. 5, the delay optical system 112 applies the first light beam L1 to the operating characteristics of the variable light attenuation optical system 113, for example, the operating characteristics (response time ) is delayed by the time corresponding to For example, as shown in FIG. 7, when the response time (time from to to t1) of each high-speed optical switch 1131, 1132, 1133 (AOE) in the variable light attenuation optical system 113 is, for example, 100 nanoseconds, The time (delay time) for delaying the pulse of the first light beam L1 is set to a time longer than the response time (the time from to to t2), for example, about 160 nanoseconds. As a result, the pulse itself of the first light beam L1 whose energy has actually been detected can pass through 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 50 meter optical path can yield a delay time of 167 nanoseconds.

5, the comparison circuit 115, the AOE drive circuit 116, and the variable light attenuation optical system 113 described above operate the delay optical system based on the energy value of the second light beam L2 detected by the energy detector 114. A stabilizer for stabilizing the energy of the first light beam L1 from the system 112 is constructed. In this stabilizer, the comparison circuit 115 and the AOE drive circuit 116 are controllers, and the larger the energy value of the second light beam L2 detected by the energy detector 114, the more the variable light 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. The comparators 115a, 115b, and 115c detect that the detected voltage values corresponding to the energy values of the second light beam L2 from the energy detector 114 are greater than the corresponding reference voltage values Ref1, Ref2, and Ref3 (Ref1>Ref2>Ref3). Outputs a comparison determination signal indicating whether or not 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 three comparison determination signals from the three comparators 115a, 115b, and 115c (comparison circuit 115). Four steps, 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 outputs three drive signals 1 in states (H level or L level) according to the energy values of the second light beam L2 in four stages represented by the three comparison determination signals from the comparison circuit 115. , 2, 3. Specifically, when the three comparison determination signals represent the 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 and 2 is set to H level, and the remaining one drive signal 3 is set to L level. When the three comparison determination signals indicate that the energy value E(V) of the second light beam L2 is the second highest level (E(Ref1)≧Ei(V)>E(Ref2)), drive signal 1 is set to H. level, and the remaining two drive signals 2 and 3 are set to L level. When the three comparison determination signals indicate that the energy value E(V) of the second light beam L2 is the third highest level (E(Ref2)≧Ei(V)>E(Ref3)), drive signal 3 is set to H. level, and the remaining two drive signals 1 and 2 are set to L level. Further, when the three comparison determination signals represent the stage where the energy value E(V) of the second light beam L2 is the lowest (Ei(V)≤E(Ref1)), all drive signals 1, 2, and 3 are Make it L level.

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

In the optical energy stabilizing device 11 described above, the energy detector 114 detects energy values Ei1, Ei2, Ei3, and Ei4 (Ei1>Ei2>Ei3>Ei4) of the second light beam L1 (incident light). FIG. 8 shows the relationship between the drive states (on state, off state) of (AOE1), 1132 (AOE2), and 1133 (AOE3) and the energy of the emitted laser beam light LB2 (emitted 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 and satisfies E(Ref2)≧Ei3>E(Ref3), and the energy value Ei4 is the smallest energy value and satisfies Ei4≦E(Ref3). is.

In the case of the detected energy value Ei1, drive signals 1 and 2 from the AOE drive circuit 116 become H level, and the remaining drive signal 3 becomes L level. As a result, the first high-speed optical switching element 1131 (AOE1) and the second high-speed optical switching element 1132 (AOE2) are turned on (ON), and the third high-speed optical switching element 1133 (AOE3) is turned off (OFF). state. In this case, each of the first high-speed optical switching element 1131 (AOE1) and the second high-speed optical switching element 1132 (AOE2) emits 85% of the 1st-order diffracted light beam and 15% of the 0th-order diffracted light beam. , the third high-speed optical switching element 1133 (AOE3) emits a 100% 0th-order diffracted light beam. As a result, the incident light beam (first light beam L1) with the energy value Ei1 passes through the light beam (Eo1) passing through the first prism attenuator 1137a (transmittance T1) and the second prism attenuator 1137b (transmittance T2). The light beam (Eo2) and the light beam (Eo4) passing through the fourth prism attenuator 1137d (transmittance T4) are separated and enter the mixer 1138. FIG. These three light beams are mixed by mixer 1138, and output laser beam light LB2 with energy value Eo is emitted from mixer 1138. FIG. 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 x (0.852 ^x T1 + 0.85 x 0.15 x T2 + 0.15 x T3) (1)
becomes.

In the case of the detected energy value Ei2, the drive signal 1 from the AOE drive circuit 116 becomes H level, and the remaining two drive signals 2 and 3 become L level. As a result, the first high-speed optical switching element 1131 (AOE1) is turned on (ON), and the two high-speed optical switching elements 1132 (AOE2) and third high-speed optical switching element 1133 (AOE3) are turned off ( OFF). In this case, the first high-speed optical switching element 1131 (AOE1) emits 85% of the 1st-order diffracted light beam and 15% of the 0th-order diffracted light beam, and the second high-speed optical switching element 1132 (AOE2) and the third A 100% zero-order diffracted light beam is emitted from each of the high-speed optical switching elements 1133 (AOE3). As a result, the incident light beam (first light beam L1) with the energy value Ei2 passes through the light beam (Eo2) passing through the second prism attenuator 1137b (transmittance T2) and the fourth prism attenuator 1137d (transmittance T4). The light beam (Eo4) and the light beam (Eo4) enter the mixer 1138 . These two light beams are mixed by mixer 1138, and output laser beam light LB2 with energy value Eo is emitted from mixer 1138. FIG. 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 x (0.85 x T2 + 0.15 x T4) (2)
becomes.

In the case of the detected energy value Ei3, drive signals 1 and 2 from the AOE drive circuit 116 become L level, and the remaining drive signal 3 becomes H level. As a result, the first high-speed optical switching element 1131 (AOE1) and the second high-speed optical switching element (AOE2) are turned off (OFF), and the third high-speed optical switching element 1133 (AOE3) is turned on (ON). Become. In this case, the first high-speed optical switching element 1131 (AOE1) emits a 100% 0th-order diffracted light beam, and the second high-speed optical switching element 1132 (AOE2) with no incident light emits a light beam. 85% of the 1st-order diffracted light beam and 15% of the 0th-order diffracted light beam are emitted from the third high-speed optical switching element 1133 (AOE3). As a result, the incident light beam (first light beam L1) with the energy value Ei3 is divided into light beams passing through the third prism attenuator 1137c (transmittance T3) and light beams passing through the fourth prism attenuator 1137d (transmittance T4). , and enter the mixer 1138 . These two light beams are mixed by mixer 1138, and output laser beam light LB2 with energy value Eo is emitted from mixer 1138. FIG. 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 x (0.85 x T3 + 0.15 x 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 L level. As a result, 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) are turned off (OFF). In this case, the first high-speed optical switch 1131 (AOE1) emits 100% 0th-order diffracted light beam, and the second high-speed optical switch element 1132 (AOE2), which has no incident light, emits light beam. 100% 0th-order diffracted light beam is emitted from the third high-speed optical switching element 1133 (AOE3). As a result, the incident light beam (first light beam L1) with energy value Ei4 enters mixer 1138 through 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 the outgoing laser beam LB2 with the 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). It will be emitted through a (higher attenuation) prism attenuator. Therefore, fluctuations in the energy value are suppressed, and the laser beam light LB2 whose energy value is stabilized can be emitted.

For example, in the above example (see FIG. 8), the varying energy value of the incident laser beam (first beam light L1) is Ei1=104
Ei2 = 102
Ei3 = 100
Ei4 = 98
and (E(Ref1)=103, E(Ref2)=101, E(Ref3)=99),
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 when .

(1) When Ei1=104 (Ei1>E(Ref1)) The energy value Eo of the emitted laser beam light LB2 calculated according to Equation (1) is
Eo = 104 x ( ^0.852 x 0.92 + 0.85 x 0.15 x 0.94 + 0.15 x 0.98) = 99.63
becomes.
(2) When Ei2=102 (E(Ref1)>Ei2≧E(Ref2)) The energy value Eo of the emitted laser beam light LB2 calculated according to Equation (2) is
Eo = 102 x (0.85 x 0.94 + 0.15 x 0.98) = 96.49
becomes.
(3) When Ei3 = 100 (E (Ref2 > Ei3 ≥ E (Ref3)) The energy value Eo of the emitted laser beam LB2 calculated according to Equation (3) is
Eo = 100 x (0.85 x 0.96 + 0.15 x 0.98) = 96.3
becomes.
(4) When Ei4=98 (Ei4≦E(Ref3)) The energy value Eo of the emitted laser beam light LB2 calculated according to Equation (4) is
Eo = 98 x 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 its variation rate is about 3%, whereas the emitted laser beam 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%. In this way, the laser beam light LB2 with its energy value stabilized by suppressing fluctuations in its energy value is emitted.

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

According to the light source device 100, the light energy stabilizing device 11 suppresses temporal fluctuations in the energy of the laser beam light LB1 emitted from the solid-state UV pulse laser 10 as the laser light source, thereby stabilizing the energy. In addition, since the diffusion optical system 12 (diffusion plate 121) is designed to relax the coherence, the energy stability is excellent, and the coherence is relaxed without the electric field intensity reaching the limit at the condensing point. It becomes possible to emit the laser beam light (exiting laser beam light).

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 composed as follows.

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

In FIG. 9, the long-axis homogenizer 14 includes a plurality of cylindrical lenses arranged in the long-axis direction DL (direction parallel to the paper surface) (each cylindrical lens extends in the short-axis direction DM perpendicular to the long-axis direction DL). ), 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 cylindrical lens pairs of the first long-axis lens array 141a and the second long-axis lens array 141b, The divided diffused laser beam light is enlarged and projected onto the long-axis projection plane S2 through the long-axis condenser lens 142 so as to be enlarged in the long-axis direction DL. Then, on the long-axis projection plane S2, a plurality of split diffused laser beams from each cylindrical lens pair 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 way, by multiplexing a plurality of split diffused laser beams on the long-axis projection plane S2, the energy distribution (intensity distribution) in the long-axis direction DL of the beam spot formed on the long-axis projection plane S2. is homogenized, for example, as shown in FIG.

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

In FIG. 11, the short-axis homogenizer 15 includes a plurality of cylindrical lenses arranged in the short-axis direction DM (direction parallel to the paper surface) perpendicular to the long-axis direction DL (each cylindrical lens is arranged in the short-axis direction DM). a first short-axis lens array 151a and a second short-axis lens array 152b, and a short-axis condenser lens 152 arranged 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 so that the incident plane of the laser beam light of the first short-axis lens array 151a coincides with the long-axis projection plane S2 (see FIG. 5). It is As a result, the laser beam light LB5 from the long-axis homogenizer 14 is projected onto the surface of the first short-axis lens array 151a as the long-axis projection plane S2 so that the beam spot extending in the long-axis direction DL is projected. The light enters the first short-axis lens array 151a. In this way, the laser beam light LB5 incident on the first short-axis lens array 151a is split (slightly diffused) by the corresponding cylindrical lens pairs of the first short-axis lens array 151a and the second short-axis lens array 151b. ), the split laser beam light LB6 is projected onto the short-axis projection plane S3 by the short-axis condenser lens 152 . A plurality of split laser beams from each cylindrical lens pair are multiplexed on the short-axis projection plane S3 to form a beam spot. By multiplexing the plurality of split laser beams LB6 on the short-axis projection plane S3 in this manner, the energy distribution (intensity distribution) of the beam spot formed on the short-axis projection plane S3 in the short-axis direction DM is equalized.

A short-axis reduction projection lens system 16 arranged after the short-axis homogenizer 15 is constructed as shown in FIG.

In FIG. 12, the short-axis reduction projection lens system 15 includes two cylindrical plano-convex lenses 161 and 162 . As described above, a plurality of split laser beams from the short-axis homogenizer 15 are multiplexed on the short-axis projection plane S3. By 162, it is collected at the focal projection plane S4 and demagnified in the minor axis direction DM (eg, 0.5 millimeters wide). In the beam spot formed on the focal point projection plane S4 by being reduced in the short axis direction DM, the laser beam light LB6 formed by multiplexing a plurality of split laser beam lights from the short axis homogenizer 15 on the short axis projection plane S3. energy homogeneity in the minor axis direction DM of is maintained.

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. A linear laser beam light LB7 is obtained as an emitted laser beam light from the line beam homogenizer.

A line beam homogenizer as described above can be used, for example, in the annealing process of semiconductor substrates. In this case, the semiconductor substrate is arranged so that the processing surface coincides with the focal point projection plane S4 (see FIG. 12), and the processing surface is irradiated with the linear laser beam light LB7 emitted from the line beam homogenizer. In this state, the semiconductor substrate and the line beam homogenizer are relatively moved in the minor axis direction DM, thereby scanning the processing surface of the semiconductor substrate with the linear laser beam light. The processing surface of the semiconductor substrate is annealed by the thermal energy of the linear laser beam light LB7 that scans the processing surface of the semiconductor substrate in the minor axis direction DM.

According to the line beam homogenizer as described above, the energy stability is excellent, the electric field intensity at the condensing point does not reach the intensity limit, and the coherence is relaxed from the laser beam light in the long axis direction and short axis direction. A line-shaped laser beam light having uniform energy distribution in both axial directions is formed. Thereby, a more stable linear laser beam light can be obtained. Therefore, by applying such a line beam homogenizer to the annealing treatment of the surface of the semiconductor substrate, the surface of the semiconductor substrate can be annealed more precisely and uniformly.

Note that the light source device 100 described above can be applied to optical devices other than the line beam homogenizer. In this case, even in the other optical device, it is possible to use a laser beam light with excellent energy stability and reduced coherence without the electric field intensity at the condensing point reaching the intensity limit.

Further, in the light source device 100 described above, the light energy stabilizing device 11 can be omitted due to the required performance of energy stability in the optical device to be used. Further, when used in an optical device in which energy stability is an important performance requirement, at least the diffusion optical system 12 out of the diffusion optical system 12 and the beam expanding optical system 13 (exiting optical system) can be omitted.

Furthermore, in the light source device 100 described above, the laser light source is not limited to the solid-state UV pulse laser 10, but may be other types such as a gas laser or a semiconductor laser, depending on the optical device to which the light source device 100 is applied. can also be used.

Instead of the beam expansion optical system 13 as the output optical system, it is also possible to use other types of output optical systems, such as collimators and other beam shaping optical systems.

In addition, the present invention is not limited to the above-described embodiment and modifications thereof. Various modifications are possible based on the gist 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 expanding optical system (exiting optical system)
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 driving 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 switching element (AOE1)
1132 second high-speed optical switching element (AOE2)
1133 third high-speed optical switching element (AOE3)
1134a, 1134b, 1134c, 1135a, 1135b, 1135c,
1136a, 1136b, 1136c Prism 1137a First prism attenuator 1137b Second prism attenuator 1137c Third prism attenuator 1137d Fourth prism attenuator

Claims (7)

A light source device having a laser light source that emits laser beam light,
a diffusion optical system for converting the laser beam light from the laser light source into a diffuse laser beam light having a predetermined diffusion angle;
an output optical system for outputting the diffused laser beam light from the diffusion optical system as output laser beam light for use in another optical device from the light source device;
The output optical system is
A light source device comprising a beam expansion optical system that expands the light diameter of the diffused laser beam light from the diffusion optical system and emits the laser beam light with the expanded light diameter. 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. 2. The light source device according to claim 1, which is equal to or less than the maximum diffusion angle. 3. The light source device according to claim 2, wherein said divergence angle of said diffused laser beam light is within a range of 10±5 milliradians. a light energy stabilizing device that suppresses temporal fluctuations in the energy of the laser beam light emitted from the laser light source and stabilizes the energy;
4. The light source device according to any one of claims 1 to 3 , wherein the laser beam light that has passed through said optical energy stabilizer enters said diffusion optical system. The optical energy stabilization device comprises:
a beam splitter that splits the laser beam light from the laser light source into a first light beam and a second light beam;
a delay optical system for delaying the first light beam obtained by the beam splitter;
an energy detector that detects the energy value of the second light beam obtained by the beam splitter;
a stabilizer that stabilizes 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;
5. The light source device according to claim 4 , wherein said first light beam whose energy has been stabilized by said stabilizer enters said diffusion optical system. the stabilizer has a variable attenuation rate, and a variable light attenuation optical system through which the first light beam from the delay optical system passes;
6. The light source device according to claim 5 , further comprising a controller that increases the attenuation rate of said variable light attenuation optical system as the energy value detected by said energy detector increases. a light source device according to any one of claims 1 to 6;
generating a linear laser beam light extending in the long axis direction with uniform energy distribution in both the long axis direction and the short axis direction orthogonal to the long axis direction from the laser beam light emitted from the light source device; A line beam homogenizer comprising a homogenizing optical system.

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